21136808 has 32 divisors (see below), whose sum is σ = 49412160. Its totient is φ = 8234880.

The previous prime is 21136807. The next prime is 21136813. The reversal of 21136808 is 80863112.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21136807) 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, 16541 + ... + 17772.

It is an arithmetic number, because the mean of its divisors is an integer number (1544130).

Almost surely, 2^21136808 is an apocalyptic number.

21136808 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

21136808 is an abundant number, since it is smaller than the sum of its proper divisors (28275352).

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

21136808 is a wasteful number, since it uses less digits than its factorization.

21136808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34337 (or 34333 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 29.

The square root of 21136808 is about 4597.4784393187. The cubic root of 21136808 is about 276.4902370257.

The spelling of 21136808 in words is "twenty-one million, one hundred thirty-six thousand, eight hundred eight".