21372656 has 10 divisors (see below), whose sum is σ = 41409552. Its totient is φ = 10686320.

The previous prime is 21372653. The next prime is 21372679. The reversal of 21372656 is 65627312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21372653) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 667880 + ... + 667911.

Almost surely, 2^21372656 is an apocalyptic number.

It is an amenable number.

21372656 is a deficient number, since it is larger than the sum of its proper divisors (20036896).

21372656 is a wasteful number, since it uses less digits than its factorization.

21372656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1335799 (or 1335793 counting only the distinct ones).

The product of its digits is 15120, while the sum is 32.

The square root of 21372656 is about 4623.0569972692. The cubic root of 21372656 is about 277.5148102368.

Adding to 21372656 its reverse (65627312), we get a palindrome (86999968).

The spelling of 21372656 in words is "twenty-one million, three hundred seventy-two thousand, six hundred fifty-six".