21582972 has 36 divisors (see below), whose sum is σ = 54699736. Its totient is φ = 7175520.

The previous prime is 21582971. The next prime is 21582973. The reversal of 21582972 is 27928512.

21582972 is a `hidden beast` number, since 2 + 1 + 582 + 9 + 72 = 666.

It is an interprime number because it is at equal distance from previous prime (21582971) and next prime (21582973).

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21582971) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 23343 + ... + 24249.

Almost surely, 2^21582972 is an apocalyptic number.

It is an amenable number.

21582972 is an abundant number, since it is smaller than the sum of its proper divisors (33116764).

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

21582972 is a wasteful number, since it uses less digits than its factorization.

21582972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1578 (or 1573 counting only the distinct ones).

The product of its digits is 20160, while the sum is 36.

The square root of 21582972 is about 4645.7477331426. The cubic root of 21582972 is about 278.4221283937.

The spelling of 21582972 in words is "twenty-one million, five hundred eighty-two thousand, nine hundred seventy-two".