21904636 has 48 divisors (see below), whose sum is σ = 44452800. Its totient is φ = 9354240.

The previous prime is 21904609. The next prime is 21904643. The reversal of 21904636 is 63640912.

It is a junction number, because it is equal to n+sod(n) for n = 21904598 and 21904607.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62590 + ... + 62938.

It is an arithmetic number, because the mean of its divisors is an integer number (926100).

Almost surely, 2^21904636 is an apocalyptic number.

21904636 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21904636 is an abundant number, since it is smaller than the sum of its proper divisors (22548164).

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

21904636 is a wasteful number, since it uses less digits than its factorization.

21904636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 454 (or 452 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 21904636 is about 4680.2388827922. The cubic root of 21904636 is about 279.7984774433.

The spelling of 21904636 in words is "twenty-one million, nine hundred four thousand, six hundred thirty-six".