21685604 has 12 divisors (see below), whose sum is σ = 38286444. Its totient is φ = 10746624.

The previous prime is 21685603. The next prime is 21685607. The reversal of 21685604 is 40658612.

It can be written as a sum of positive squares in 2 ways, for example, as 11888704 + 9796900 = 3448^2 + 3130^2 .

It is not an unprimeable number, because it can be changed into a prime (21685603) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23537 + ... + 24440.

It is an arithmetic number, because the mean of its divisors is an integer number (3190537).

Almost surely, 2^21685604 is an apocalyptic number.

It is an amenable number.

21685604 is a deficient number, since it is larger than the sum of its proper divisors (16600840).

21685604 is a wasteful number, since it uses less digits than its factorization.

21685604 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 48094 (or 48092 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 32.

The square root of 21685604 is about 4656.7804328742. The cubic root of 21685604 is about 278.8627511457.

The spelling of 21685604 in words is "twenty-one million, six hundred eighty-five thousand, six hundred four".