21057304 has 8 divisors (see below), whose sum is σ = 39482460. Its totient is φ = 10528648.

The previous prime is 21057299. The next prime is 21057307. The reversal of 21057304 is 40375012.

It is a tau number, because it is divible by the number of its divisors (8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21057307) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1316074 + ... + 1316089.

Almost surely, 2^21057304 is an apocalyptic number.

It is an amenable number.

21057304 is a deficient number, since it is larger than the sum of its proper divisors (18425156).

21057304 is a wasteful number, since it uses less digits than its factorization.

21057304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2632169 (or 2632165 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21057304 is about 4588.8238144431. The cubic root of 21057304 is about 276.1431379639.

It can be divided in two parts, 2105 and 7304, that added together give a square (9409 = 97²).

The spelling of 21057304 in words is "twenty-one million, fifty-seven thousand, three hundred four".