21593864 has 16 divisors (see below), whose sum is σ = 41885100. Its totient is φ = 10424512.

The previous prime is 21593863. The next prime is 21593867. The reversal of 21593864 is 46839512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20884900 + 708964 = 4570^2 + 842^2 .

It is not an unprimeable number, because it can be changed into a prime (21593863) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 46307 + ... + 46770.

Almost surely, 2^21593864 is an apocalyptic number.

It is an amenable number.

21593864 is a deficient number, since it is larger than the sum of its proper divisors (20291236).

21593864 is a wasteful number, since it uses less digits than its factorization.

21593864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93112 (or 93108 counting only the distinct ones).

The product of its digits is 51840, while the sum is 38.

The square root of 21593864 is about 4646.9198400661. The cubic root of 21593864 is about 278.4689564183.

The spelling of 21593864 in words is "twenty-one million, five hundred ninety-three thousand, eight hundred sixty-four".