21157204 has 12 divisors (see below), whose sum is σ = 37886464. Its totient is φ = 10332504.

The previous prime is 21157139. The next prime is 21157207. The reversal of 21157204 is 40275112.

It is a happy number.

It is a hoax number, since the sum of its digits (22) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21157207) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 61332 + ... + 61675.

Almost surely, 2^21157204 is an apocalyptic number.

It is an amenable number.

21157204 is a deficient number, since it is larger than the sum of its proper divisors (16729260).

21157204 is a wasteful number, since it uses less digits than its factorization.

21157204 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123054 (or 123052 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21157204 is about 4599.6960769164. The cubic root of 21157204 is about 276.5791416822.

The spelling of 21157204 in words is "twenty-one million, one hundred fifty-seven thousand, two hundred four".