List of perfect numbers. The following is a list of the known perfect numbers, along with the Mersenne prime exponent p which generates them with the expression 2pâ1Ã (2p â 1) where 2p â 1 is a Mersenne prime. All even perfect numbers are of this form. It is not known whether there are any odd perfect numbers. As of 2016 there are 49 known perfect numbers in total. The ratio p / digits approaches log(10) / log(4) = 1.6609640474...