About
PrimeGrid's primary goal is to advance mathematics by enabling everyday computer users to contribute their system's processing power towards prime finding. By simply
downloading and installing BOINC and attaching to the PrimeGrid project,
participants can choose from a variety of prime forms to search. With a little patience, you may find a large or even record
breaking prime and enter into Chris Caldwell's The Largest Known Primes Database with a multi-million digit prime!
PrimeGrid's secondary goal is to provide relevant educational materials about primes. Additionally, we wish to contribute to the
field of mathematics.
Lastly, primes play a central role in the cryptographic systems which are used for computer security. Through the study of prime
numbers it can be shown how much processing is required to crack an encryption code and thus to determine whether current
security schemes are sufficiently secure. PrimeGrid is currently running several sub-projects:
- 321 Prime Search: searching for
mega primes of the form 3·2n±1.
- Cullen-Woodall Search: searching for
mega primes of forms n·2n+1 and
n·2n−1.
- Generalized Cullen-Woodall Search: searching for mega primes of forms n·bn+1 and
n·bn−1 where n + 2 > b.
- Extended Sierpinski Problem: helping solve the Extended Sierpinski Problem.
- Generalized Fermat Prime Search: searching for
megaprimes of the form b2n+1.
- Prime Sierpinski Project: helping the Prime Sierpinski Project solve the Prime Sierpinski Problem.
- Proth Prime Search: searching for primes of the form k·2n+1.
- Fermat Divisor Search: a subset of the Proth Prime Search specificically searching for divisors of
Fermat numbers.
- Seventeen or Bust: helping to solve the Sierpinski Problem.
- Sierpinski/Riesel Base 5: helping to solve the Sierpinski/Riesel Base 5 Problem.
- Sophie Germain Prime Search: searching for primes p and 2p+1.
- The Riesel problem: helping to solve the Riesel Problem.
- AP27 Search: searching for record length arithmetic progressions of primes.
Recent Significant Primes
On 27 January 2021, 17:13:11 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime
25·28456828+1
The prime is 2,545,761 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 74 th overall.
The discovery was made by Wolfgang Schwieger ( DeleteNull) of Germany using an AMD Ryzen 7 3700X 8-Core Processor with 16GB RAM, running Microsoft Windows 10 Professional x64 Edition.
This computer took about 1 hour, 20 minutes to complete the primality test using LLR2. Wolfgang Schwieger is a member of the SETI.Germany team.
For more information, please see the Official Announcement.
On 23 January 2021, 03:37:22 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime
39·28413422+1
The prime is 2,532,694 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 74 th overall.
The discovery was made by Philipp Bliedung ( pabliedung) using an Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz with 1GB RAM, running Linux Ubuntu.
This computer took about 2 hours, 5 minutes to complete the primality test using LLR2. Philipp Bliedung is a member of the USA team.
For more information, please see the Official Announcement.
On 20 January 2021, 11:58:27 UTC, PrimeGrid's 321 Search found the Mega Prime
3·216819291-1
The prime is 5,063,112 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 21 st overall.
The discovery was made by Rudi Tapper ( ruditapper) of the United Kingdom using an AMD Ryzen Threadripper 3990X 64-Core Processor with 16GB RAM, running Microsoft Windows 10 Professional x64 Edition.
This computer took about 5 hours, 40 minutes to complete the primality test using LLR2. Rudi Tapper is a member of the Antarctic Crunchers team.
For more information, please see the Official Announcement.
On 19 January 2021, 15:48:46 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime
31·28348000+1
The prime is 2,513,000 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 73 rd overall.
The discovery was made by Igor Karpenko ( A1ex01) of Ukraine using an Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz with 4GB RAM, running Linux.
This computer took about 2 hours, 52 minutes to complete the primality test using LLR2. Igor Karpenko is a member of the Ukraine team.
For more information, please see the Official Announcement.
On 14 January 2021, 18:15:44 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime
27·27963247+1 Divides F(7963245)
The prime is 2,397,178 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 74 th overall. This is ranked 2 nd for prime Fermat divisors, and it is also ranked 2 nd for "weighted" prime Fermat divisors.
The discovery was made by Tom Greer ( tng) of the United States using an Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz with 1GB RAM, running Linux Ubuntu.
This computer took about 3 hours, 58 minutes to complete the primality test using LLR2. Tom Greer is a member of the Antarctic Crunchers team.
For more information, please see the Official Announcement.
On 14 January 2021, 14:16:38 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime
39·27946769+1
The prime is 2,392,218 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 74 th overall.
The discovery was made by Scott Brown ( Scott Brown) of the United States using an Intel(R) Xeon(R) CPU E5-2697 v2 @ 2.70GHz with 120GB RAM, running Microsoft Windows 10 Professional x64 Edition.
This computer took about 4 hours, 15 minutes to complete the primality test using LLR2. Scott Brown is a member of the Aggie The Pew team.
For more information, please see the Official Announcement.
On 14 January 2021, 04:06:53 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime
29·27899985+1
The prime is 2,378,134 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 76 th overall.
The discovery was made by Tom Greer ( tng) of the United States using an Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz with 16GB RAM, running Microsoft Windows 10 Core x64 Edition.
This computer took about 2 hours, 1 minute to complete the primality test using LLR2. Tom Greer is a member of the Antarctic Crunchers team.
For more information, please see the Official Announcement.
On 13 December 2020, 16:07:34 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
45·27661004+1
The prime is 2,306,194 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 77 th overall.
The discovery was made by Tim Terry ( TimT) of the United States using an Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60GHz with 32GB RAM, running Linux Fedora.
This computer took about 1 hour, 10 minutes to complete the primality test using LLR2. Tim Terry is a member of the Aggie The Pew team.
For more information, please see the Official Announcement.
On 6 December 2020, 02:07:48 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
15·27619838+1
The prime is 2,293,801 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 78 th overall.
The discovery was made by an anonymous user of China using an Intel(R) Core(TM) i5-4590 CPU @ 3.30GHz with 16GB RAM, running Microsoft Windows 10 Professional x64 Edition.
This computer took about 2 hours to complete the primality test using LLR2.
For more information, please see the Official Announcement.
Other significant primes
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News 
Another DIV Mega Prime!
On 27 January 2021, 17:13:11 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
25*2^8456828+1
The prime is 2,545,761 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 74th overall.
The discovery was made by Wolfgang Schwieger (DeleteNull) of Germany using an AMD Ryzen 7 3700X 8-Core Processor with 16GB RAM, running Microsoft Windows 10 Professional x64 Edition. This computer took about 1 hour, 20 minutes to complete the primality test using LLR2. Wolfgang Schwieger is a member of the SETI.Germany team.
For more details, please see the official announcement.
1 Feb 2021 | 15:37:44 UTC
· Comment
And Another DIV Mega Prime!
On 23 January 2021, 03:37:22 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
39*2^8413422+1
The prime is 2,532,694 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 74th overall.
The discovery was made by Philipp Bliedung (pabliedung) using an Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz with 1GB RAM, running Linux Ubuntu Ubuntu 18.04.3 LTS [4.15.0-72-generic|libc 2.27 (Ubuntu GLIBC 2.27-3ubuntu1.2)]. This computer took about 2 hours, 5 minutes to complete the primality test using LLR2. Philipp Bliedung is a member of the USA team.
For more details, please see the official announcement.
1 Feb 2021 | 15:13:44 UTC
· Comment
321 Mega Prime!
On 20 January 2021, 11:58:27 UTC, PrimeGrid's 321 Search found the Mega Prime:
3*2^16819291-1
The prime is 5,063,112 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 21st overall.
The discovery was made by Rudi Tapper (ruditapper) of the United Kingdom using an AMD Ryzen Threadripper 3990X 64-Core Processor with 16GB RAM, running Microsoft Windows 10 Professional x64 Edition. This computer took about 5 hours, 40 minutes to complete the primality test using LLR2. Rudi Tapper is a member of the Antarctic Crunchers team.
For more details, please see the official announcement.
1 Feb 2021 | 13:49:02 UTC
· Comment
Another DIV Mega Prime!
On 19 January 2021, 15:48:46 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
31*2^8348000+1
The prime is 2,513,000 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 73rd overall.
The discovery was made by Igor Karpenko (A1ex01) of Ukraine using an Intel(R) Core(TM) i5-8400 CPU @ 2.80GHz with 4GB RAM, running Linux. This computer took about 2 hours, 52 minutes to complete the primality test using LLR. Igor Karpenko is a member of the Ukraine team.
For more details, please see the official announcement.
1 Feb 2021 | 3:24:19 UTC
· Comment
Fermat Divisor Found!
On 14 January 2021, 18:15:44 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
27*2^7963247+1 Divides F(7963245)
The prime is 2,397,178 digits long and will enter Chris Caldwell's The Largest Known Primes Database ranked 74th overall. This is ranked 2nd for prime Fermat divisors, and it is also ranked 2nd for “weighted” prime Fermat divisors.
The discovery was made by Tom Greer (tng) of the United States using an Intel(R) Xeon(R) Gold 6140 CPU @ 2.30GHz with 1GB RAM, running Linux Ubuntu. This computer took about 3 hours, 58 minutes to complete the primality test using LLR2. Tom Greer is a member of the Antarctic Crunchers team.
For more details, please see the official announcement.
1 Feb 2021 | 3:17:46 UTC
· Comment
... more
News is available as an RSS feed 
Newly reported primes(Mega-primes are in bold.)
5978342141457*2^1290000-1 (Krzysiak_PL_GDA); 87547832^131072+1 (DeleteNull); 5978255175417*2^1290000-1 (spnorton); 122809274^65536+1 (CelticNinja); 5977916328195*2^1290000-1 (vaughan); 224057990^32768+1 (WezH); 224029504^32768+1 (SEARCHER); 5971610012667*2^1290000-1 (Yegor001); 5972959488597*2^1290000-1 (vaughan); 223899674^32768+1 (Johny); 25*2^8788628+1 (tng); 87454694^131072+1 (beslade); 122745454^65536+1 (4bc3); 5974003281447*2^1290000-1 (Krzysiak_PL_GDA); 122700492^65536+1 (4bc3); 5971550429775*2^1290000-1 (akeda); 122691846^65536+1 (McDaWisel); 223736638^32768+1 (SEARCHER); 5972382270045*2^1290000-1 (vaughan); 5972264505795*2^1290000-1 (Shayol Ghul) Top Crunchers:Top participants by RAC | Top teams by RAC |
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