Numbers that are less than the sum of their proper divisors. For example, 8 is a deficient number, since its proper divisors are 1, 2, and 4, and 1 + 2 + 4 = 7, which is less than 8.
Numbers that are less than the sum of their proper divisors. For example, 8 is a deficient number, since its proper divisors are 1, 2, and 4, and 1 + 2 + 4 = 7, which is less than 8.