21173172 has 12 divisors (see below), whose sum is σ = 49404096. Its totient is φ = 7057720.

The previous prime is 21173167. The next prime is 21173203. The reversal of 21173172 is 27137112.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 882204 + ... + 882227.

It is an arithmetic number, because the mean of its divisors is an integer number (4117008).

Almost surely, 2^21173172 is an apocalyptic number.

It is an amenable number.

21173172 is an abundant number, since it is smaller than the sum of its proper divisors (28230924).

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

21173172 is a wasteful number, since it uses less digits than its factorization.

21173172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1764438 (or 1764436 counting only the distinct ones).

The product of its digits is 588, while the sum is 24.

The square root of 21173172 is about 4601.4315163870. The cubic root of 21173172 is about 276.6487051451.

The spelling of 21173172 in words is "twenty-one million, one hundred seventy-three thousand, one hundred seventy-two".