21399536 has 20 divisors (see below), whose sum is σ = 42166200. Its totient is φ = 10517952.

The previous prime is 21399527. The next prime is 21399541. The reversal of 21399536 is 63599312.

It is a self number, because there is not a number n which added to its sum of digits gives 21399536.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10391 + ... + 12278.

It is an arithmetic number, because the mean of its divisors is an integer number (2108310).

Almost surely, 2^21399536 is an apocalyptic number.

It is an amenable number.

21399536 is a deficient number, since it is larger than the sum of its proper divisors (20766664).

21399536 is a wasteful number, since it uses less digits than its factorization.

21399536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22736 (or 22730 counting only the distinct ones).

The product of its digits is 43740, while the sum is 38.

The square root of 21399536 is about 4625.9632510430. The cubic root of 21399536 is about 277.6311032705.

The spelling of 21399536 in words is "twenty-one million, three hundred ninety-nine thousand, five hundred thirty-six".