21657052 has 6 divisors (see below), whose sum is σ = 37899848. Its totient is φ = 10828524.

The previous prime is 21657049. The next prime is 21657067. The reversal of 21657052 is 25075612.

It is a self number, because there is not a number n which added to its sum of digits gives 21657052.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2707128 + ... + 2707135.

Almost surely, 2^21657052 is an apocalyptic number.

It is an amenable number.

21657052 is a deficient number, since it is larger than the sum of its proper divisors (16242796).

21657052 is a wasteful number, since it uses less digits than its factorization.

21657052 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5414267 (or 5414265 counting only the distinct ones).

The product of its (nonzero) digits is 4200, while the sum is 28.

The square root of 21657052 is about 4653.7137857844. The cubic root of 21657052 is about 278.7403106823.

The spelling of 21657052 in words is "twenty-one million, six hundred fifty-seven thousand, fifty-two".