21085808 has 20 divisors (see below), whose sum is σ = 41851488. Its totient is φ = 10285440.

The previous prime is 21085789. The next prime is 21085837. The reversal of 21085808 is 80858012.

It is a super-2 number, since 2×21085808² = 889222598025728, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15416 + ... + 16727.

Almost surely, 2^21085808 is an apocalyptic number.

It is an amenable number.

21085808 is a deficient number, since it is larger than the sum of its proper divisors (20765680).

21085808 is a wasteful number, since it uses less digits than its factorization.

21085808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32192 (or 32186 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 32.

The square root of 21085808 is about 4591.9285708730. The cubic root of 21085808 is about 276.2676812117.

The spelling of 21085808 in words is "twenty-one million, eighty-five thousand, eight hundred eight".