21857204 has 12 divisors (see below), whose sum is σ = 38645124. Its totient is φ = 10815744.

The previous prime is 21857203. The next prime is 21857221. The reversal of 21857204 is 40275812.

It can be written as a sum of positive squares in 2 ways, for example, as 3794704 + 18062500 = 1948^2 + 4250^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21857203) 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, 27779 + ... + 28554.

It is an arithmetic number, because the mean of its divisors is an integer number (3220427).

Almost surely, 2^21857204 is an apocalyptic number.

It is an amenable number.

21857204 is a deficient number, since it is larger than the sum of its proper divisors (16787920).

21857204 is a wasteful number, since it uses less digits than its factorization.

21857204 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56434 (or 56432 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 29.

The square root of 21857204 is about 4675.1688739552. The cubic root of 21857204 is about 279.5963742270.

The spelling of 21857204 in words is "twenty-one million, eight hundred fifty-seven thousand, two hundred four".