21413664 has 36 divisors (see below), whose sum is σ = 60895926. Its totient is φ = 7137792.

The previous prime is 21413647. The next prime is 21413677. The reversal of 21413664 is 46631412.

It can be written as a sum of positive squares in only one way, i.e., 16160400 + 5253264 = 4020^2 + 2292^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a nude number because it is divisible by every one of its digits.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 36889 + ... + 37464.

Almost surely, 2^21413664 is an apocalyptic number.

21413664 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21413664 is an abundant number, since it is smaller than the sum of its proper divisors (39482262).

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

21413664 is a wasteful number, since it uses less digits than its factorization.

21413664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74369 (or 74358 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 21413664 is about 4627.4900324042. The cubic root of 21413664 is about 277.6921872953.

The spelling of 21413664 in words is "twenty-one million, four hundred thirteen thousand, six hundred sixty-four".