On 19 Apr 2012, 21:12:27 UTC, PrimeGrid’s Generalized Fermat Prime Search, through PRPNet, found the mega prime: 773620^262144+1
The prime is 1,543,643 digits long and enters Chris Caldwell's “The Largest Known Primes Database” ranked 2nd for Generalized Fermat primes and 22nd overall.
The discovery was made by Senji Yamashita of Japan using an NVIDIA GeForce GTX 580 in an Intel Core i7-970 @ 3.20GHz system with 6GB RAM, running Windows 7 Professional x64. This GPU took about 47 minutes to probable prime (PRP) test with GenefCUDA. Senji is a member of the PrimeSearchTeam.
For more details, please see the official announcement.