21663136 has 24 divisors (see below), whose sum is σ = 46527264. Its totient is φ = 9846720.

The previous prime is 21663127. The next prime is 21663139. The reversal of 21663136 is 63136612.

It is a super-2 number, since 2×21663136² = 938582922708992, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21663139) 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, 30420 + ... + 31123.

It is an arithmetic number, because the mean of its divisors is an integer number (1938636).

Almost surely, 2^21663136 is an apocalyptic number.

It is an amenable number.

21663136 is an abundant number, since it is smaller than the sum of its proper divisors (24864128).

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

21663136 is a wasteful number, since it uses less digits than its factorization.

21663136 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 61564 (or 61556 counting only the distinct ones).

The product of its digits is 3888, while the sum is 28.

The square root of 21663136 is about 4654.3674113675. The cubic root of 21663136 is about 278.7664099142.

Adding to 21663136 its reverse (63136612), we get a palindrome (84799748).

The spelling of 21663136 in words is "twenty-one million, six hundred sixty-three thousand, one hundred thirty-six".