A whole number that is equal to the sum of its positive factors, excluding the number itself.
Example: 28
Its positive factors are {1, 2, 4, 7, 14, 28}. Excluding the 28 the sum is 1 + 2 + 4 + 7 + 14 = 28, so 28 is a Perfect Number.
A whole number that is equal to the sum of its positive factors, excluding the number itself.
Example: 28
Its positive factors are {1, 2, 4, 7, 14, 28}. Excluding the 28 the sum is 1 + 2 + 4 + 7 + 14 = 28, so 28 is a Perfect Number.