Largest known probable prime Mersenne Cofactors  (proper divisor of 2p-1 with p prime)

 Cofactor

 Digits

 When

 Found by

 (2684127-1)/23765203727

 205933  

 04/2009  

 Jens Kruse Andersen

 (2406583-1)/813167

 122388  

 02/2009  

 Jens Kruse Andersen

 (2271549-1)/238749682487

 81734  

 02/2009  

 Jens Kruse Andersen

 (2271211-1)/613961495159

 81631  

 02/2009  

 Jens Kruse Andersen

 (2221509-1)/292391881

 66673  

 02/2009  

 Jens Kruse Andersen

 (2173867-1)/52536637502689

 52326  

 06/2005  

 Donovan Johnson

 (2136883-1)/536581361

 41198

 05/2005

 Donovan Johnson

 (2130439-1)/260879

 39261

 05/2005

 Donovan Johnson

 (2106391-1)/286105171290931103

 32010

 05/2005

 Donovan Johnson

 (286371-1)/41681512921035887

 25984

 05/2005

 Donovan Johnson

 (263703-1)/42808417

 19169

 05/2005

 Donovan Johnson

 (258199-1)/237604901713907577052391    

 17497

 05/2005

 Donovan Johnson


The smaller factor of each Mersenne number was obtained from Will Edgington's Mersenne Page. All probable prime cofactors on this page are listed on Henri Lifchitz's Top 10000 PRPs page. Click here to view.


20 largest known prime Mersenne cofactors (The Prime Pages)
Biography of Marin Mersenne
Main page


Last updated on May 12, 2009
Donovan Johnson