As of April 6, 2000 one award has been given.

Presently, the largest known prime number is the over-two-million-digit prime 2^6972593-1, a.k.a. M(6972593) or the 38th Mersenne Prime. This prime was discovered by Nayan Hajratwala, using software written by George Woltman and the distributed computing technology and services of Scott Kurowski's company, Entropia.com, Inc., via GIMPS - a cooperative computing group, officially known as the Great Internet Mersenne Prime Search.

Prior to this discovery, the largest known prime number was the 909526-digit prime 2^3021377-1, a.k.a. M(3021377) or the 37th Mersenne Prime. This prime number was discovered by Roland Clarkson, George Woltman, and Scott Kurowski via GIMPS

According to the GIMPS status page, all Mersenne numbers that are 1,000,000 decimal digits or shorter have been tested at least once.

Selected pre-award timeline

• 26 Dec 1998
  According to the GIMPS status page, all Mersenne numbers with less than 1,000,000 decimal digits have been tested once. Only 37 Mersenne primes have been discovered throughout history. Most, but not all of sub-million digit Mersenne numbers have been double tested. There is a slight chance that a sub-million digit Mersenne prime was missed.
  
  
• 27 Jan 1998
  Clarkson, Woltman, Kurowski & GIMPS discover the 909526 digit prime M3021377 (2^3021377-1) using a collection of computers across the Internet.
  
  
• 1 Apr 1992
  The first 100,000+ digit prime: M756839 (2⁷⁵⁶⁸³⁹-1) is discovered by Slowinski and Gage.
  
  This record surpassed the 65087 digit prime 391581 * 2²¹⁵¹⁹³-1 which was discovered by the Amdahl 6 on 6 Aug 1989 using the Amdahl 1200 computer.
  
  
• 4 Apr 1979
  The first 10,000+ digit prime M44497 (2⁴⁴⁴⁹⁷-1) is discovered by Nelson and Slowinski.
  
  This record surpassed the 6987 digit prime M23209 (2^M23209-1) which was discovered by Noll on 9 Feb 1979 using a Cyber 174 computer.
  
  
• 11 Mar 1961
  The first 1,000+ digit prime M4423 (2⁴⁴²³-1) is discovered by Hurwitz and Selfridge.
  
  This record surpassed the 969 digit prime M3217 (2³²¹⁷-1) which was discovered by Riesel in 1957 on the using the BESK computer.
  
  
• 30 Jan 1952
  The first 100+ digit prime M521 (2⁵²¹-1) is discovered by Robinson and Lehmer using the SWAC computer.
  
  This record surpassed the 79 digit prime 180*(M127)²+1 (180 * (2⁵²¹-1)² + 1), the first ``largest known prime'' that was discovered on a digital computer (by Miller & Wheeler using the EDSAC1 in 1951).
  
  
• 1867
  The first 10+ digit prime M59/179551 (2⁵⁹-1 / 179551) is discovered by Landry using brute force trial division.
  
  This record surpassed a 10 digit prime M31 (2³¹-1, also proven also using brute force trial division) by Euler in 1772.
  
  

For more information

Press release about the awards program (Mar. 31, 1999)
Official rules for the awards
Cooperative Computing Award News
Frequently Asked Questions about the awards
Prime Number Resources and Information