Bits and Beyond ...
An integer is called a perfect number if it is equal to the sum of
all of its positive factors, excluding itself. The first perfect
number is 6 because 6=1+2+3, where 1, 2 and 3 are the factors of 6. The next is
28 because 28=1+2+4+7+14. The next two are 496 and 8128.