21633808 has 40 divisors (see below), whose sum is σ = 48121920. Its totient is φ = 9229440.

The previous prime is 21633803. The next prime is 21633827. The reversal of 21633808 is 80833612.

It is a plaindrome in base 11.

It is a self number, because there is not a number n which added to its sum of digits gives 21633808.

It is not an unprimeable number, because it can be changed into a prime (21633803) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 46698 + ... + 47158.

It is an arithmetic number, because the mean of its divisors is an integer number (1203048).

Almost surely, 2^21633808 is an apocalyptic number.

21633808 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21633808 is an abundant number, since it is smaller than the sum of its proper divisors (26488112).

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

21633808 is a wasteful number, since it uses less digits than its factorization.

21633808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 895 (or 889 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The square root of 21633808 is about 4651.2157550473. The cubic root of 21633808 is about 278.6405531976.

The spelling of 21633808 in words is "twenty-one million, six hundred thirty-three thousand, eight hundred eight".