On 26 April 2019, 13:27:42 UTC, PrimeGrid’s Sierpiński/Riesel Base 5 Problem project eliminated k=138514 by finding the mega prime:
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.