21530856 has 16 divisors (see below), whose sum is σ = 53827200. Its totient is φ = 7176944.

The previous prime is 21530849. The next prime is 21530867. The reversal of 21530856 is 65803512.

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, 448536 + ... + 448583.

It is an arithmetic number, because the mean of its divisors is an integer number (3364200).

Almost surely, 2^21530856 is an apocalyptic number.

It is an amenable number.

21530856 is an abundant number, since it is smaller than the sum of its proper divisors (32296344).

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

21530856 is a wasteful number, since it uses less digits than its factorization.

21530856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 897128 (or 897124 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 21530856 is about 4640.1353428537. The cubic root of 21530856 is about 278.1978475340.

The spelling of 21530856 in words is "twenty-one million, five hundred thirty thousand, eight hundred fifty-six".