In mathematics, a perfect number is an integer that is the sum of all of its proper, positive divisors not including the number itself. The first perfect number is 6, because 1, 2, and 3 are its proper, positive divisors and 1+2+3=6. Euclid, a Hellenistic mathematician living in the third century BCE, discovered a formula that identifies the first four perfect numbers. What is the second number in this set? Discuss
Source: The Free Dictionary