---
title: "PrimeGrid"
chunk: 2/2
source: "https://en.wikipedia.org/wiki/PrimeGrid"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T04:12:31.751416+00:00"
instance: "kb-cron"
---

=== Riesel Problem ===
As of 13 December 2022, PrimeGrid has eliminated 18 values of k from the Riesel problem
and is continuing the search to eliminate the 43 remaining numbers. 3 values of k are found by independent searchers.

=== Twin prime search ===
Primegrid worked with the Twin Prime Search to search for a record-sized twin prime at approximately 58,700 digits. The new world's largest known twin prime 2003663613 × 2195000 ± 1 was eventually discovered on January 15, 2007 (sieved by Twin Prime Search and tested by PrimeGrid). The search continued for another record twin prime at just above 100,000 digits. It was completed in August 2009 when PrimeGrid found 65516468355 × 2333333 ± 1. Continued testing for twin primes in conjunction with the search for a Sophie Germain prime yielded a new record twin prime in September 2016 upon finding the number 2996863034895 × 21290000 ± 1 composed of 388,342 digits.

=== Woodall prime search ===
As of 22 April 2018, the project has discovered the four largest Woodall primes known to date.
The largest of these is 17016602 × 217016602  − 1 and was found on 21 March 2018. The search continues for an even bigger Woodall prime.
PrimeGrid also found the largest known generalized Woodall prime,
563528 × 13563528 − 1.

== Media coverage ==
PrimeGrid's author Rytis Slatkevičius has been featured as a young entrepreneur in The Economist.
PrimeGrid has also been featured in an article by Francois Grey in the CERN Courier and a talk about citizen cyberscience in TEDx Warwick conference.
In the first Citizen Cyberscience Summit, Rytis Slatkevičius gave a talk as a founder of PrimeGrid, named Finding primes: from digits to digital technology,
relating mathematics and volunteering and featuring the history of the project.

== References ==

== External links ==
Official website 
PrimeGrid Discord chat server (almost daily discovery announcements)
PrimeGrid's results at The Prime Pages