21173988 has 24 divisors (see below), whose sum is σ = 53897760. Its totient is φ = 6416320.

The previous prime is 21173987. The next prime is 21174001. The reversal of 21173988 is 88937112.

It is not an unprimeable number, because it can be changed into a prime (21173983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 80073 + ... + 80336.

It is an arithmetic number, because the mean of its divisors is an integer number (2245740).

Almost surely, 2^21173988 is an apocalyptic number.

It is an amenable number.

21173988 is an abundant number, since it is smaller than the sum of its proper divisors (32723772).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21173988 is a wasteful number, since it uses less digits than its factorization.

21173988 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 160427 (or 160425 counting only the distinct ones).

The product of its digits is 24192, while the sum is 39.

The square root of 21173988 is about 4601.5201835915. The cubic root of 21173988 is about 276.6522590520.

It can be divided in two parts, 2117 and 3988, that added together give a triangular number (6105 = T₁₁₀).

The spelling of 21173988 in words is "twenty-one million, one hundred seventy-three thousand, nine hundred eighty-eight".