21663536 has 20 divisors (see below), whose sum is σ = 42283752. Its totient is φ = 10751616.

The previous prime is 21663527. The next prime is 21663547. The reversal of 21663536 is 63536612.

It is a super-3 number, since 3×21663536³ (a number of 23 digits) contains 333 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2750 + ... + 7133.

Almost surely, 2^21663536 is an apocalyptic number.

It is an amenable number.

21663536 is a deficient number, since it is larger than the sum of its proper divisors (20620216).

21663536 is a wasteful number, since it uses less digits than its factorization.

21663536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10028 (or 10022 counting only the distinct ones).

The product of its digits is 19440, while the sum is 32.

The square root of 21663536 is about 4654.4103815628. The cubic root of 21663536 is about 278.7681256689.

The spelling of 21663536 in words is "twenty-one million, six hundred sixty-three thousand, five hundred thirty-six".