Whole number for which the sum of its proper divisors is less than the number itself.

### Examples

- Consider the number 81.

The sum of its proper divisors is 40, because: 1 + 3 + 9 + 27 = 40.

Because 40 < 81, this means that 81 is a deficient number. - Consider the whole number 20.

The sum of its proper divisors is 22, because: 1 + 2 + 4 + 5 + 10 = 22.

Because 22 > 20, this means that 20 is not a deficient number.