21252564 has 48 divisors (see below), whose sum is σ = 58004800. Its totient is φ = 6710688.

The previous prime is 21252551. The next prime is 21252571. The reversal of 21252564 is 46525212.

It is a Harshad number since it is a multiple of its sum of digits (27).

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, 3127 + ... + 7230.

Almost surely, 2^21252564 is an apocalyptic number.

It is an amenable number.

21252564 is an abundant number, since it is smaller than the sum of its proper divisors (36752236).

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

21252564 is a wasteful number, since it uses less digits than its factorization.

21252564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10389 (or 10381 counting only the distinct ones).

The product of its digits is 4800, while the sum is 27.

The square root of 21252564 is about 4610.0503251049. The cubic root of 21252564 is about 276.9940525338.

Adding to 21252564 its reverse (46525212), we get a palindrome (67777776).

The spelling of 21252564 in words is "twenty-one million, two hundred fifty-two thousand, five hundred sixty-four".