21587916 has 48 divisors (see below), whose sum is σ = 57867264. Its totient is φ = 6135936.

The previous prime is 21587893. The next prime is 21587921. The reversal of 21587916 is 61978512.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19021 + ... + 20123.

It is an arithmetic number, because the mean of its divisors is an integer number (1205568).

Almost surely, 2^21587916 is an apocalyptic number.

It is an amenable number.

21587916 is an abundant number, since it is smaller than the sum of its proper divisors (36279348).

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

21587916 is a wasteful number, since it uses less digits than its factorization.

21587916 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1350 (or 1348 counting only the distinct ones).

The product of its digits is 30240, while the sum is 39.

The square root of 21587916 is about 4646.2798021643. The cubic root of 21587916 is about 278.4433861073.

The spelling of 21587916 in words is "twenty-one million, five hundred eighty-seven thousand, nine hundred sixteen".