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 12 November 2020, 06:43:56 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
45·27513661+1
The prime is 2,261,839 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 73 rd overall.
The discovery was made by Hiroyuki Okazaki ( zunewantan) of Japan using an Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60GHz with 32GB RAM, running Linux.
This computer took about 2 hours, 6 minutes to complete the primality test using LLR2. Hiroyuki Okazaki is a member of the Aggie The Pew team.
For more information, please see the Official Announcement.
On 27 October 2020, 22:38:04 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
29·27374577+1
The prime is 2,219,971 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 73 rd overall.
The discovery was made by Pavel Atnashev ( Pavel Atnashev) of Russia using an Intel(R) Xeon(R) E5-2660 v2 CPU @ 2.20GHz with 4GB RAM, running Linux.
This computer took about 1 hour, 49 minutes to complete the primality test using LLR2. Pavel Atnashev is a member of the Ural Federal University team.
For more information, please see the Official Announcement.
On 25 October 2020, 11:30:07 UTC, PrimeGrid's 321 Prime Search found the Mega Prime:
3·216408818+1
The prime is 4,939,547 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 21 st overall.
The discovery was made by Scott Brown ( Scott Brown) of the United States using an Intel(R) Core(TM) i7-4770S CPU @ 3.10GHz with 8GB RAM, running Microsoft Windows 10 Enterprise x64 Edition. This computer took about 6 hours, 6 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 25 October 2020, 00:52:15 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
15·27300254+1
The prime is 2,197,597 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 75 th overall.
The discovery was made by Robert Gelhar ( Gelly) 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, 24 minutes to complete the primality test using LLR2.
Robert Gelhar is a member of the Antarctic Crunchers team.
For more information, please see the Official Announcement.
On 24 October 2020, 22:53:39 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
19·26833086+1
The prime is 2,056,966 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 94 th overall.
The discovery was made by Jiri Jaros ( Venec) of the Czech Republic using an Intel(R) Xeon(R) CPU E5-2620 v3 @ 2.40GHz with 8GB RAM, running Linux Ubuntu. This computer took about 7 hours, 27 minutes to complete the primality test using LLR2.
Jiri Jaros is a member of the Czech National Team.
For more information, please see the Official Announcement.
On 20 October 2020, 19:06:13 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
39·26684941+1
The prime is 2,012,370 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 97 th overall.
The discovery was made by Mike Thümmler ( fnord) of Germany using an AMD Ryzen 5 1600X Six-Core Processor with 16GB RAM, running Microsoft Windows 10 Professional x64 Edition. This computer took about 4 hours to complete the primality test using LLR2.
Mike Thümmler is a member of the SETI.Germany team.
For more information, please see the Official Announcement.
On 20 October 2020, 13:22:13 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
39·26648997+1
The prime is 2,001,550 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 99 th overall.
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 2 hours, 38 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.
Other significant primes
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News 
New Subproject!
For the first time in a while, we have a new subproject: the Wieferich and Wall-Sun-Sun Prime Search!
To participate, edit your project preferences. The app is available for GPU and CPU.
Note: there may be severe screen lag on the GPU Mac version. We are aware and a fix will be out soon.
See this forum thread for more information about the search.
28 Nov 2020 | 23:20:08 UTC
· Comment
TRP Mega Prime!
On 16 November 2020, 23:17:01 UTC, PrimeGrid’s The Riesel Problem project eliminated k=146561 by finding the mega prime:
146561*2^11280802-1
The prime is 3,395,865 digits long and will enter Chris Caldwell's The Largest Known Primes Database ranked 42nd overall. This is PrimeGrid's 16th elimination. 48 k's now remain.
The discovery was made by Pavel Atnashev (Pavel Atnashev) of Russia using an Intel(R) Xeon(TM) E5-2680 v4 CPU @ 2.40GHz with 4GB RAM, running Linux. This computer took about 3 hours, 18 minutes to complete the primality test using LLR2. Pavel Atnashev is a member of the Ural Federal University team.
For more details, please see the official announcement.
25 Nov 2020 | 14:19:31 UTC
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DIV Mega Prime!
On 12 November 2020, 06:43:56 UTC, PrimeGrid's Fermat Divisor Search found the Mega Prime:
45*2^7513661+1
The prime is 2,261,839 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 73rd overall.
The discovery was made by Hiroyuki Okazaki (zunewantan) of Japan using an Intel(R) Xeon(R) CPU E5-2670 0 @ 2.60GHz with 32GB RAM, running Linux 4.4.0-21-generic. This computer took about 2 hours, 6 minutes to complete the primality test using LLR. Hiroyuki Okazaki is a member of the Aggie The Pew team.
For more details, please see the official announcement.
18 Nov 2020 | 19:00:30 UTC
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Magellan 500th Anniversary Challenge starts 18 November
The eighth challenge of the 2020 Series will be a 10-day challenge commemorating the (approximate) 500th Anniversary of the extraordinary expedition of Portuguese explorer Ferdinand Magellan. The challenge will be offered on the CUL-LLR and WOO-LLR subprojects, beginning 18 November 18:00 UTC and ending 28 November 18:00 UTC.
To participate in the Challenge, please select only the Cullen Prime Search LLR (CUL) and/or Woodall Prime Search LLR (WOO) projects in your PrimeGrid preferences section. Work units which are downloaded and completed during the challenge will count towards your challenge score.
Note: This will be our second challenge using LLR2, which eliminates the need for a full doublecheck task on each workunit, but replaces it with a short verification task. Expect to receive a few tasks about 1% of normal length.
Comments? Concerns? Conundrums? Confusions? Think we'll break the decade-long drought of Cullen primes? Tell us in the forum thread for this challenge. Best of luck!
16 Nov 2020 | 2:46:34 UTC
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321 Sieve is over
The 321 Sieve project has come to an end, and no more 321 Sieve tasks will be sent out.
If you currently have only 321-Sieve tasks selected, I suggest switching to the PPS-Sieve project. It's a similar task, albeit longer in duration.
4 Nov 2020 | 18:05:12 UTC
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Newly reported primes(Mega-primes are in bold.)
5409*2^1611070+1 (pudge94); 5752227750087*2^1290000-1 (Penguin); 206355000^32768+1 (Christoph); 206346962^32768+1 (Juergen); 5751675578577*2^1290000-1 (Margus); 206325772^32768+1 (mikey); 5753561761425*2^1290000-1 (YuW3-810); 5753182596315*2^1290000-1 (Todderbert); 5751409779255*2^1290000-1 (ruditapper); 5742253457505*2^1290000-1 (Viktor Svantner); 5751705680745*2^1290000-1 (Penguin); 8989*2^3340866+1 (Charles Jackson); 206118026^32768+1 (Richard McCormack); 2031*2^1611007+1 (Randall J. Scalise); 6631*2^3340808+1 (mackerel); 99316110^65536+1 (Sashixi); 5748814502007*2^1290000-1 (Krzysiak_PL_GDA); 5747699064915*2^1290000-1 (YuW3-810); 5748688082007*2^1290000-1 (Dr. Berthold Schaefer); 2505*2^1610980+1 (CGB) Top Crunchers:Top participants by RAC | Top teams by RAC |
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