21308856 has 32 divisors (see below), whose sum is σ = 55589760. Its totient is φ = 6793952.

The previous prime is 21308831. The next prime is 21308867. The reversal of 21308856 is 65880312.

It is a happy number.

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 7 ways as a sum of consecutive naturals, for example, 18750 + ... + 19853.

It is an arithmetic number, because the mean of its divisors is an integer number (1737180).

Almost surely, 2^21308856 is an apocalyptic number.

It is an amenable number.

21308856 is an abundant number, since it is smaller than the sum of its proper divisors (34280904).

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

21308856 is a wasteful number, since it uses less digits than its factorization.

21308856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38635 (or 38631 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 33.

The square root of 21308856 is about 4616.1516439563. The cubic root of 21308856 is about 277.2383964270.

The spelling of 21308856 in words is "twenty-one million, three hundred eight thousand, eight hundred fifty-six".