how to get perfect number

If, for some k > 1, 2^k - 1 is prime then 2^k-1(2^k - 1) is a perfect number

For instance, the first perfect number, 6   =  2^(2 - 1) (2^2  - 1)  =  2^1 ( 3)   = 6

So far, only even perfect numbers have been found......no one knows if there are any odd ones...if there are, the above formula would not applly......[it produces only even numbers ]

Here's a fascinating look at perfect numbers........http://www-history.mcs.st-and.ac.uk/HistTopics/Perfect_numbers.html