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 26 April 2019, 13:27:42 UTC, PrimeGrid's Sierpiński/Riesel Base 5 Problem project eliminated k=138514 by finding the mega prime:
138514 · 5 2771922 + 1
The prime is 1,937,496 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 63 rd overall and is the largest known base 5 prime. 31 k's now remain in the Sierpiński Base 5 problem.
The discovery was made by Ken Ito ( jpldcon4) of the Japan
using an Intel(R) Core(TM) i9-9820X CPU @ 3.30GHz with 32 GB of RAM, running Microsoft Windows 10 Professional x64 Edition.
This computer took about 2 hours and 46 minutes to primality test using multithreaded LLR.
Ken is a member of Team 2ch.
For more information, please see the Official Announcement.
On 17 April 2019, 11:00:27 UTC, PrimeGrid's Generalized Fermat Prime Search found the Generalized Fermat mega prime:
2788032 524288 + 1
The prime is 3,379,193 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 3 rd for Generalized Fermat primes and 26 th overall.
The discovery was made by Ed Goforth ( BlisteringSheep) of the Netherlands Antilles
using an NVIDIA GeForce GTX 760 in an Intel(R) Xeon(R) CPU E5-2687W v3 @ 3.10GHz with 128GB RAM, running Linux.
This GPU took about 3 hours and 30 minutes to probable prime (PRP) test with GeneferOCL5.
Ed is a member of the Christians team.
The PRP was confirmed prime by an Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz with 16GB RAM, running Microsoft Windows 10 Professional x64 Edition.
This computer took about 25 hours and 3 minutes to complete the primality test using multithreaded LLR.
For more information, please see the Official Announcement.
On 18 March 2019, 07:26:42 UTC, PrimeGrid's Generalized Fermat Prime Search found the Generalized Fermat mega prime:
2733014 524288 + 1
The prime is 3,374,655 digits long and enters Chris Caldwell's The Largest Known Primes Database
ranked 3 rd for Generalized Fermat primes and 26 th overall.
The discovery was made by Yair Givoni ( Yair Givoni) of Israel
using an NVIDIA GeForce GTX 960 in an Intel(R) Core(TM) i5-6600 CPU @ 3.30GHz with 16GB RAM, running Windows 10 Core x64 Edition.
This GPU took about 2 hours and 57 minutes to probable prime (PRP) test with GeneferOCL3.
Yair is a member of The Planetary Society team.
The PRP was confirmed prime by an Intel(R) Xeon(R) CPU E3-1240 v6 @ 3.70GHz with 4GB RAM, running Linux Debian.
This computer took about 26 hours and 43 minutes to complete the primality test using multithreaded LLR.
For more information, please see the Official Announcement.
Other significant primes
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News 
Hans Ivar Riesel's 90th Birthday Challenge starts May 24th 2019 00:00 UTC
To celebrate Hans Ivar Riesel's birthday, PrimeGrid is having a 7 day challenge from May 24th 2019, 00:00 UTC until May 31st, 00:00 UTC.
Work units from the TRP (LLR) project, which are downloaded and completed during the challenge will count towards your challenge score.
Help us celebrate, maybe find a really big prime number eliminating one of the Riesel k's for Riesel's birthday and earn a cool new badge!
Best estimate is 30% chance someone finds a prime during the challenge.
For more information and discussion, please see the official challenge thread: http://www.primegrid.com/forum_thread.php?id=8556
23 May 2019 | 9:29:54 UTC
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AVX-512 Now Supported by LLR
All of PrimeGrid's LLR applications now support AVX-512 on CPUs with that capability. Those of you that have been using app_info.xml/anonymous platform to run LLR 3.8.23 may now use the stock app if you wish, which is also LLR 3.8.23.
UPDATE May 22nd: It has come to my attention that while CPUs with 2 AVX-512 execution units gain a substantial boost in performance, mid-range CPUs with only 1 AVX-512 execution unit may see a significant decrease in performance with the new LLR app. Obviously, this is not intended. For the time being there is no workaround for this. If you have a CPU that supports AVX-512, but has only a single AVX-512 execution unit, you may want to use the anonymous platform mechanism (app_info.xml) to run the older version of LLR. With a challenge starting tomorrow, we won't make changes to the app until at least a week. We apologize for any inconvenience this may cause.
UPDATE May 23rd: I've included a list of single and dual unit AVX-512 CPUs here.
22 May 2019 | 0:22:04 UTC
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Reason you should upgrade BOINC
"If it ain't broke, don't fix it" isn't a terrible rule of thumb, but not in this case.
We've just updated most of PrimeGrid's apps, but to take advantage of them you'll need to be running a version of BOINC that isn't too ancient.
On the apps that use wrappers (currently all of the LLR apps and 321-Sieve) the priority of the wrapper is increased above idle priority. This may help avoid some infrequent crashes attributed to the wrapper. You'll need at least BOINC 7.4.0+ (first released in 2014) to take advantage of this feature. The LLR apps are already updated, and 321-Sieve will be updated in the near future.
All of the binary files will now be sent gzipped, which will reduce data transfer by about 50%. You'll need at least BOINC 7.0.0+ (first released in 2012) to take advantage of this feature.
If you're running a really old version of BOINC, you now have a reason to upgrade!
EDIT: There's been some confusion about how version numbers work. 7.14.2, released in October 2018, is the most recent version of BOINC as of right now, and is what you should be running. "14" comes after "4". 7.14.x is new, 7.4.x is quite old, and 7.0.x is even older!
8 May 2019 | 13:03:36 UTC
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New SR5 Mega Prime!
On 26 April 2019, 13:27:42 UTC, PrimeGrid’s Sierpiński/Riesel Base 5 Problem project eliminated k=138514 by finding the mega prime:
138514*5^2771922+1
The prime is 1,937,496 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 63rd overall and is the largest known base 5 prime. 31 k’s now remain in the Sierpiński Base 5 problem.
The discovery was made by Ken Ito (jpldcon4) of Japan using an Intel(R) Core(TM) i9-9820X CPU @ 3.30GHz with 32 GB of RAM, running Microsoft Windows 10 Professional x64 Edition. This computer took 2 hours and 46 minutes to complete the primality test using multithreaded LLR. Ken is a member of Team 2ch.
The prime was verified on 27 April 2019, 07:28:26 UTC by Dmitry Domanov (unconnected) of Russia using an Intel(R) Core(TM) i5-2310 CPU @ 2.90GHz with 3 GB of RAM, running Microsoft Windows XP Professional x86 Edition. This computer took about 23 hours and 24 minutes to complete the primality test using LLR. Dmitry is a member of the Russia team.
For more details, please see the official announcement.
28 Apr 2019 | 4:50:56 UTC
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GFN-524288 Mega Prime!
On 17 Apr 2019, 11:00:27 UTC, PrimeGrid’s Generalized Fermat Prime Search found the Generalized Fermat mega prime:
2788032^524288+1
The prime is 3,379,193 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 3rd for Generalized Fermat primes and 26th overall.
The discovery was made by Ed Goforth (BlisteringSheep) of the Netherlands Antilles using an NVIDIA GeForce GTX 760 in an Intel(R) Xeon(R) CPU E5-2687W v3 @ 3.10GHz CPU with 128GB RAM, running Linux. This GPU took about 3 hours 31 minutes to probable prime (PRP) test with GeneferOCL5. Ed is a member of the Christians team.
The prime was verified on 23 Apr 2019, 13:36:35 by Brent Schneider (KWSN-SpongeBob SquarePants) of Nepal using an NVIDIA GeForce GTX 1080 in an Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz with 16GB RAM, running Windows 10. This GPU took about 1 hour 17 minutes to probable prime (PRP) test with GeneferOCL5. Brent is a member of The Knights Who Say Ni! team.
The PRP was confirmed prime by an Intel(R) Core(TM) i7-7700K CPU @ 4.20GHz with 16GB RAM, running Windows 10. This computer took about 25 hours 4 minutes to complete the primality test using multithreaded LLR.
For more details, please see the official announcement.
26 Apr 2019 | 12:30:54 UTC
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Newly reported primes(Mega-primes are in bold.)
126286018^32768+1 (Johny); 126243998^32768+1 (candido); 4464606872847*2^1290000-1 (candido); 62555084^65536+1 (Troy Wigginton); 62554864^65536+1 (meilijo); 126113708^32768+1 (Johny); 126081182^32768+1 (Johny); 126055746^32768+1 (Metin Sariyar); 501*2^2728224+1 (Randall J. Scalise); 693*2^2728537+1 (Randall J. Scalise); 125904228^32768+1 (Philipp Schulz); 4459862081265*2^1290000-1 (Darryl); 15342502^131072+1 (tng*); 4456975333737*2^1290000-1 (candido); 62479964^65536+1 (Spear); 62464130^65536+1 (Fire$torm [BlackOps]); 9157*2^1539526+1 (Honza); 125847628^32768+1 (Kellen); 4461860156325*2^1290000-1 (trebotuet); 753*2^3631472+1 (288larsson) 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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