On 21 March 2018, 22:13:39 UTC, PrimeGrid’s Woodall Prime Search found the Woodall mega prime:
Woodall numbers are of the form: W(n)=n*2^n-1. Woodall numbers that are prime are called Woodall primes. For more information, please see “Woodall prime” in The Prime Glossary (http://primes.utm.edu/glossary).
The prime is 5,122,515 digits long and enters Chris Caldwell's The Largest Known Primes Database ranked 1st for Woodall primes and 16th overall. This is the 4th largest prime found by PrimeGrid, the 4th Woodall prime found by PrimeGrid, and the first Woodall prime found since December, 2007.
The discovery was made by Diego Bertolotti (ScOrPIoN) of Italy using an Intel(R) Core(TM) i7-2600 CPU at 3.40GHz with 8GB RAM, running Microsoft Windows 10. This computer took about 4 days 6 hours 14 minutes to complete the primality test. Diego is a member of the Boinc @ Italy team.
For more details, please see the official announcement.