12 JAN 2012 by ideonexus

 2,305,843,008,139,952,128 is the Greatest Perfect Number ...

230(231-1) ... is the greatest perfect number known at present, and probably the greatest that ever will be discovered; for; as they are merely curious without being useful, it is not likely that any person will attempt to find a number beyond it.
  1  notes

231-1 = 2147483647 is a prime number, and a number on which this number relies. The prime number is the largest value for a 32-bit signed integer. Barlow believed no prime greater than this would be discovered as there was no point.