21585972 has 24 divisors (see below), whose sum is σ = 51440256. Its totient is φ = 7042048.

The previous prime is 21585961. The next prime is 21585973. The reversal of 21585972 is 27958512.

It is a hoax number, since the sum of its digits (39) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21585972.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21585973) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18573 + ... + 19700.

It is an arithmetic number, because the mean of its divisors is an integer number (2143344).

Almost surely, 2^21585972 is an apocalyptic number.

It is an amenable number.

21585972 is an abundant number, since it is smaller than the sum of its proper divisors (29854284).

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

21585972 is a wasteful number, since it uses less digits than its factorization.

21585972 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38327 (or 38325 counting only the distinct ones).

The product of its digits is 50400, while the sum is 39.

The square root of 21585972 is about 4646.0705978278. The cubic root of 21585972 is about 278.4350278790.

The spelling of 21585972 in words is "twenty-one million, five hundred eighty-five thousand, nine hundred seventy-two".