M41 is the short hand used to refer to the 41st Mersenne prime 224,036,583-1.
M41 was discovered to be prime on 2004-05-15 by Josh Findley, using Prime95 written by George Woltman. At the time of discovery, it was the largest known prime number. The number is 7,816,230 decimal digits long. This prime number was the seventh record prime found by the GIMPS project.
The discovery took 14 days of computing on 2.4 GHz Pentium 4 Windows XP PC.
The new prime was independently verified:
- by Tony Reix of Grenoble, France using half of a Bull NovaScale 5000 HPC running Linux on 16 Itanium II 1.3 GHz CPUs for five days using the Glucas program by Guillermo Ballester Valor of Granada, Spain;
- by Jeff Gilchrist of Elytra Enterprises Inc. in Ottawa, Canada using eleven days of time on a HP rx5670 quad Itanium II 1.5 GHz CPU server at SHARCNET.
- GIMPS Discovers 41st Mersenne Prime (press release)