21023808 has 56 divisors (see below), whose sum is σ = 59911488. Its totient is φ = 6468096.

The previous prime is 21023791. The next prime is 21023813. The reversal of 21023808 is 80832012.

It is a Harshad number since it is a multiple of its sum of digits (24).

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 in 7 ways as a sum of consecutive naturals, for example, 1716 + ... + 6707.

It is an arithmetic number, because the mean of its divisors is an integer number (1069848).

Almost surely, 2^21023808 is an apocalyptic number.

It is an amenable number.

21023808 is an abundant number, since it is smaller than the sum of its proper divisors (38887680).

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

21023808 is a wasteful number, since it uses less digits than its factorization.

21023808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8451 (or 8441 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 21023808 is about 4585.1726248856. The cubic root of 21023808 is about 275.9966393206.

Adding to 21023808 its product of nonzero digits (768), we get a cube (21024576 = 276³).

The spelling of 21023808 in words is "twenty-one million, twenty-three thousand, eight hundred eight".