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 as
a Titan!
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.
- 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 Prime Sierpinski Project solve the Prime Sierpinski Problem.
- Proth Prime Search: searching for primes of the form k·2n+1.
- 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.
Recent Significant Primes
On 17 October 2017, 13:48:48 UTC, PrimeGrid's PPS Mega Prime Search project found the mega prime:
1147·23435970+1
The prime is 1,034,334 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 208 th overall.
The discovery was made by Randall Scalise ( Randall J. Scalise) of the United States
using an Intel(R) Core(TM) i5-4590 CPU @ 3.30GHz with 8GB RAM, running Linux. This computer took about 1 hour and 6 minutes to complete the primality test using LLR.
For more information, please see the Official Announcement.
On 5 October 2017, 08:47:45 UTC, PrimeGrid's PPS Mega Prime Search project found the mega prime:
911·23432643+1
The prime is 1,033,331 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 208 th overall.
The discovery was made by Jochen Beck ( dh1saj) of Germany
using an Intel(R) Core(TM) i5-4670 CPU @ 3.40GHz with 8GB RAM, running Windows 7 Professional Edition. This computer took about 1 hour and 25 minutes to complete the primality test using LLR.
Jochen is a member of the SETI.Germany team.
For more information, please see the Official Announcement.
On 17 September 2017, 21:30:08 UTC, PrimeGrid's Prime Sierpinski Problem project eliminated k=168451 by finding the mega prime:
168451·219375200+1
The prime is 5,832,522 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 13 th overall.
9 k's now remain in the Prime Sierpinski Problem (2 of which are being searched as part of Seventeen or Bust). This is the third largest prime found by PrimeGrid.
Until the Prime Sierpinski Project shut down in 2014, this search was a collaboration between Primegrid and the Prime Sierpinski Project.
This discovery would not have been possible without all the work done over the years by the Prime Sierpinski Project.
The discovery was made by Ben Maloney ( paleseptember) of Australia
using an Intel(R) Core(TM) i5-6400 CPU @ 2.70GHz with 16GB RAM running Windows 10 Professional Edition. This computer took about 2 days, 15 hours and 11 minutes to complete the primality test using LLR.
Ben is a member of the Free-DC team.
For more information, please see the Official Announcement.
On 17 August 2017, 20:18:24 UTC, PrimeGrid's Sierpinski/Riesel Base 5 Problem project eliminated k=301562 by finding the mega prime:
301562·52408646-1
The prime is 1,683,577 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 57 th overall. 72 k's now remain in the Riesel Base 5 Problem.
The discovery was made by Håkan Lind ( sangis43) of Sweden
using an Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz with 32 GB RAM running Microsoft Windows 7 Professional Edition. This computer took about 43 hours and 57 minutes to complete the primality test using LLR.
Håkan is a member of the Sicituradastra. team.
For more information, please see the Official Announcement.
On 14 September 2017, 23:21:35 UTC, PrimeGrid's Generalized Fermat Prime Search found the Generalized Fermat mega prime:
47179704131072+1
The prime is 1,005,815 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 26 th for Generalized Fermat Primes and 250 th overall.
The discovery was made by Andrei Okhrimouk ( AndreiO) of Australia
using an NVIDIA Geforce GTX 960 series GPU in an Intel(R) Core(TM)2 Dup CPU at 2.80GHz with 4GB RAM, running Microsoft Windows 10 Professional Edition.
This GPU took about 21 minutes to complete the probable prime (PRP) test using GeneferOCL2.
For more information, please see the Official Announcement.
Other significant primes
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News 
Another PPS-Mega Prime!
On 17 October 2017, 13:48:48 UTC, PrimeGrid’s PPS Mega Prime Search project found the Mega Prime:
1147*2^3435970+1
The prime is 1,034,334 digits long and will enter Chris Caldwell's The Largest Known Primes Database ranked 208th overall.
The discovery was made by Randall Scalise (Randall J. Scalise) of the United States using an Intel(R) Core(TM) i5-4590 CPU @ 3.30GHz with 8GB RAM, running Linux. This computer took about 1 hour 6 minutes to complete the primality test using LLR.
The prime was verified on 17 October 2017, 14:57:02 UTC by Amy Chambers (Buckeye74) of the United States using an Intel(R) Core(TM) i7-4770K CPU @ 3.50GHz with 16GB RAM, running Microsoft Windows 10 Core Edition. This computer took about 1 hour 13 minutes to complete the primality test using LLR. Amy is a member of the Sigma Omicron Chapter of Tau Kappa Epsilon team.
For more details, please see the official announcement.
18 Oct 2017 | 18:30:25 UTC
· Comment
Diwali/Deepavali Challenge Starts Today!
Please note the start time of this challenge: 00:00:00
This is 18 hours earlier than usual. Don't be late!
Help us celebrate Diwali/Deepavali by participating in our 5 day challenge on the Riesel Problem LLR sub-project.
The challenge starts at 00:00:00 UTC tomorrow, October 18th (that's about 7 hours from now), and ends in 5 days at 00:00:00 UTC on October 23rd.
The last prime eliminating a k in the Riesel Problem was found on October 4th, 2014 -- just over three years ago!
For more information, please see the official challenge thread: http://www.primegrid.com/forum_thread.php?id=7623
17 Oct 2017 | 16:55:44 UTC
· Comment
Another PPS-Mega Prime!
On 5 October 2017, 08:47:45 UTC, PrimeGrid’s PPS Mega Prime Search project found the Mega Prime:
911*2^3432643+1
The prime is 1,033,331 digits long and will enter Chris Caldwell's The Largest Known Primes Database ranked 208th overall.
The discovery was made by Jochen Beck (dh1saj) of Germany using an Intel(R) Core(TM) i5-4670 CPU @ 3.40GHz with 8GB RAM, running Windows 7 Professional Edition. This computer took about 1 hour 25 minutes to complete the primality test using LLR. Jochen is a member of the SETI.Germany team.
The prime was verified on 6 October 2017, 22:29:00 UTC by Georgios Magklaras (georgios) of Greece using an Intel(R) Xeon(R) E5-2650 v3 CPU @ 2.30GHz with 128GB RAM, running Linux. This computer took about 2 hours 28 minutes to complete the primality test using LLR. Georgios is a member of the Team Norway team.
For more details, please see the official announcement.
9 Oct 2017 | 13:15:21 UTC
· Comment
PRPNet server set to "No New Work"
As part of our upcoming server move, effective immediately PRPNet will not be giving out new work. Jobs in progress can still be returned for credit, but no more new tasks will be sent out from the server.
This only affects the PRPNet server. The BOINC server is not affected by this change.
Please see this thread for more information and discussion.
5 Oct 2017 | 15:09:27 UTC
· Comment
New SR5 Mega Prime!
On 17 September 2017, 20:18:24 UTC, PrimeGrid’s Sierpinski/Riesel Base 5 Problem project eliminated k=301562 by finding the mega prime:
301562*5^2408646-1
The prime is 1,683,577 digits long and will enter Chris Caldwell's The Largest Known Primes Database ranked 57th overall. 72 k's now remain in the Riesel Base 5 Problem.
The discovery was made by Håkan Lind (sangis43) of Sweden using an Intel(R) Core(TM) i7-5820K CPU @ 3.30GHz with 32 GB RAM running Microsoft Windows 7 Professional Edition. This computer took about 43 hours 57 minutes to complete the primality test using LLR. Håkan is a member of the Sicituradastra. Team.
For more details, please see the official announcement.
Double-checker information TBA.
29 Sep 2017 | 14:22:32 UTC
· Comment
... more
News is available as an RSS feed 
Newly reported primes3763567605525*2^1290000-1 (Randall J. Scalise); 62751960^32768+1 (admitflash); 62647522^32768+1 (Kwartet!); 3763030255455*2^1290000-1 (蔡修偉); 1147*2^3435970+1 (Randall J. Scalise); 62537488^32768+1 (Vortac); 7889*2^1459863+1 (Scott Brown); 3761945859327*2^1290000-1 (Randall J. Scalise); 62422592^32768+1 (GeoffreyY); 3758288136867*2^1290000-1 (zunewantan); 2193*2^1459700+1 (evaotaku00); 62327894^32768+1 (Roadranner); 62318154^32768+1 (DaveSun); 3756865004235*2^1290000-1 (zunewantan); 3750844144887*2^1290000-1 (Krzysiak_PL_GDA); 62137258^32768+1 (boss); 62105082^32768+1 (nic); 3750677675607*2^1290000-1 (Máté Börcsök); 62094976^32768+1 (Roadranner); 3749706282045*2^1290000-1 (SEK) Last 24 hoursTop participants by work done in the last 24 hours | Top teams by work done in the last 24 hours |
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