Examples

• Consider the number 496. The sum of its proper divisors is 496, because: 1 + 2 + 4 + 8 + 16 + 31 + 62 + 124 + 248 = 496. Therefore, 496 is a perfect number.
• Consider the whole number 20. The sum of its proper divisors is 22, because: 1 + 2 + 4 + 5 + 10 = 22. Because 22 > 20, 22 is an abundant number.
• Consider the number 81. The sum of its proper divisors is 40 because: 1 + 3 + 9 + 27 = 40. Because 40 < 81, 81 is a deficient number.
• The numbers 6 and 28 are also perfect numbers.