21512684 has 12 divisors (see below), whose sum is σ = 39861864. Its totient is φ = 10123584.

The previous prime is 21512669. The next prime is 21512713. The reversal of 21512684 is 48621512.

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, 158114 + ... + 158249.

It is an arithmetic number, because the mean of its divisors is an integer number (3321822).

Almost surely, 2^21512684 is an apocalyptic number.

It is an amenable number.

21512684 is a deficient number, since it is larger than the sum of its proper divisors (18349180).

21512684 is a wasteful number, since it uses less digits than its factorization.

21512684 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316384 (or 316382 counting only the distinct ones).

The product of its digits is 3840, while the sum is 29.

The square root of 21512684 is about 4638.1767969753. The cubic root of 21512684 is about 278.1195593600.

The spelling of 21512684 in words is "twenty-one million, five hundred twelve thousand, six hundred eighty-four".