21725920 has 24 divisors (see below), whose sum is σ = 51327864. Its totient is φ = 8690304.

The previous prime is 21725903. The next prime is 21725933. The reversal of 21725920 is 2952712.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 67734 + ... + 68053.

It is an arithmetic number, because the mean of its divisors is an integer number (2138661).

Almost surely, 2^21725920 is an apocalyptic number.

21725920 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21725920 is an abundant number, since it is smaller than the sum of its proper divisors (29601944).

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

21725920 is a wasteful number, since it uses less digits than its factorization.

21725920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135802 (or 135794 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21725920 is about 4661.1071646123. The cubic root of 21725920 is about 279.0354566689.

The spelling of 21725920 in words is "twenty-one million, seven hundred twenty-five thousand, nine hundred twenty".