On 13 December 2017, 07:13:55 UTC, PrimeGrid’s The Riesel Problem project eliminated k=273809 by finding the mega prime:
The prime is 2,688,931 digits long and will enter Chris Caldwell's The Largest Known Primes Database ranked 29th overall. This is PrimeGrid's 15th elimination. 49 k's now remain.
The discovery was made by Wolfgang Schwieger (DeleteNull) of Germany using an Intel(R) Core(TM) i7-6700K CPU @ 4.00GHz with 32 GB RAM running Linux. This computer took about 2 hours and 14 minutes to complete the primality test using multithreaded LLR. Wolfgang is a member of the SETI.Germany team.
The prime was verified on 15 December 2017, 11:39:55 UTC, by Christian Geffcken (CGe0963) of Switzerland using an Intel(R) Core(TM) i5-3437U CPU @ 1.90GHz with 8 GB RAM running Microsoft Windows 7 Professional. This computer took about 41 hours and 47 minutes to complete the primality test using LLR.
For more details, please see the official announcement.