21564204 has 12 divisors (see below), whose sum is σ = 50316504. Its totient is φ = 7188064.

The previous prime is 21564203. The next prime is 21564217. The reversal of 21564204 is 40246512.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (21564203) 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, 898497 + ... + 898520.

It is an arithmetic number, because the mean of its divisors is an integer number (4193042).

Almost surely, 2^21564204 is an apocalyptic number.

It is an amenable number.

21564204 is an abundant number, since it is smaller than the sum of its proper divisors (28752300).

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

21564204 is a wasteful number, since it uses less digits than its factorization.

21564204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1797024 (or 1797022 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 24.

The square root of 21564204 is about 4643.7273821791. The cubic root of 21564204 is about 278.3414020713.

The spelling of 21564204 in words is "twenty-one million, five hundred sixty-four thousand, two hundred four".