21903808 has 28 divisors (see below), whose sum is σ = 45755560. Its totient is φ = 10374912.

The previous prime is 21903793. The next prime is 21903811. The reversal of 21903808 is 80830912.

It is a self number, because there is not a number n which added to its sum of digits gives 21903808.

It is a congruent number.

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, 7791 + ... + 10222.

Almost surely, 2^21903808 is an apocalyptic number.

It is an amenable number.

21903808 is an abundant number, since it is smaller than the sum of its proper divisors (23851752).

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

21903808 is a wasteful number, since it uses less digits than its factorization.

21903808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18044 (or 18034 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 31.

The square root of 21903808 is about 4680.1504249329. The cubic root of 21903808 is about 279.7949519178.

The spelling of 21903808 in words is "twenty-one million, nine hundred three thousand, eight hundred eight".