21025808 has 10 divisors (see below), whose sum is σ = 40737534. Its totient is φ = 10512896.

The previous prime is 21025793. The next prime is 21025811. The reversal of 21025808 is 80852012.

It can be written as a sum of positive squares in only one way, i.e., 13778944 + 7246864 = 3712^2 + 2692^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 657041 + ... + 657072.

Almost surely, 2^21025808 is an apocalyptic number.

It is an amenable number.

21025808 is a deficient number, since it is larger than the sum of its proper divisors (19711726).

21025808 is a wasteful number, since it uses less digits than its factorization.

21025808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1314121 (or 1314115 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 26.

The square root of 21025808 is about 4585.3907139959. The cubic root of 21025808 is about 276.0053909190.

The spelling of 21025808 in words is "twenty-one million, twenty-five thousand, eight hundred eight".