21256972 has 48 divisors (see below), whose sum is σ = 43706880. Its totient is φ = 8942400.

The previous prime is 21256931. The next prime is 21256997. The reversal of 21256972 is 27965212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39022 + ... + 39562.

It is an arithmetic number, because the mean of its divisors is an integer number (910560).

Almost surely, 2^21256972 is an apocalyptic number.

21256972 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21256972 is an abundant number, since it is smaller than the sum of its proper divisors (22449908).

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

21256972 is a wasteful number, since it uses less digits than its factorization.

21256972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 622 (or 620 counting only the distinct ones).

The product of its digits is 15120, while the sum is 34.

The square root of 21256972 is about 4610.5283862048. The cubic root of 21256972 is about 277.0132016802.

The spelling of 21256972 in words is "twenty-one million, two hundred fifty-six thousand, nine hundred seventy-two".