21585316 has 27 divisors (see below), whose sum is σ = 39882913. Its totient is φ = 10221200.

The previous prime is 21585283. The next prime is 21585337. The reversal of 21585316 is 61358512.

The square root of 21585316 is 4646.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 20738916 + 846400 = 4554^2 + 920^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 213666 + ... + 213766.

Almost surely, 2^21585316 is an apocalyptic number.

21585316 is the 4646-th square number.

It is an amenable number.

21585316 is a deficient number, since it is larger than the sum of its proper divisors (18297597).

21585316 is a wasteful number, since it uses less digits than its factorization.

21585316 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 252 (or 126 counting only the distinct ones).

The product of its digits is 7200, while the sum is 31.

The cubic root of 21585316 is about 278.4322072936.

The spelling of 21585316 in words is "twenty-one million, five hundred eighty-five thousand, three hundred sixteen".