21057252 has 24 divisors (see below), whose sum is σ = 49463232. Its totient is φ = 6972000.

The previous prime is 21057247. The next prime is 21057287. The reversal of 21057252 is 25275012.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 3999 + ... + 7622.

It is an arithmetic number, because the mean of its divisors is an integer number (2060968).

Almost surely, 2^21057252 is an apocalyptic number.

It is an amenable number.

21057252 is an abundant number, since it is smaller than the sum of its proper divisors (28405980).

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

21057252 is a wasteful number, since it uses less digits than its factorization.

21057252 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11779 (or 11777 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21057252 is about 4588.8181484997. The cubic root of 21057252 is about 276.1429106563.

The spelling of 21057252 in words is "twenty-one million, fifty-seven thousand, two hundred fifty-two".