21812008 has 32 divisors (see below), whose sum is σ = 42213600. Its totient is φ = 10559808.

The previous prime is 21811987. The next prime is 21812017. The reversal of 21812008 is 80021812.

It is a self number, because there is not a number n which added to its sum of digits gives 21812008.

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 7 ways as a sum of consecutive naturals, for example, 55878 + ... + 56266.

It is an arithmetic number, because the mean of its divisors is an integer number (1319175).

Almost surely, 2^21812008 is an apocalyptic number.

It is an amenable number.

21812008 is a deficient number, since it is larger than the sum of its proper divisors (20401592).

21812008 is a wasteful number, since it uses less digits than its factorization.

21812008 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 601 (or 597 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 21812008 is about 4670.3327504579. The cubic root of 21812008 is about 279.4035261741.

The spelling of 21812008 in words is "twenty-one million, eight hundred twelve thousand, eight".