21057512 has 32 divisors (see below), whose sum is σ = 47088000. Its totient is φ = 8631744.

The previous prime is 21057511. The next prime is 21057521. The reversal of 21057512 is 21575012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is not an unprimeable number, because it can be changed into a prime (21057511) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6887 + ... + 9462.

It is an arithmetic number, because the mean of its divisors is an integer number (1471500).

Almost surely, 2^21057512 is an apocalyptic number.

It is an amenable number.

21057512 is an abundant number, since it is smaller than the sum of its proper divisors (26030488).

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

21057512 is a wasteful number, since it uses less digits than its factorization.

21057512 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16385 (or 16381 counting only the distinct ones).

The product of its (nonzero) digits is 700, while the sum is 23.

The square root of 21057512 is about 4588.8464781468. The cubic root of 21057512 is about 276.1440471905.

The spelling of 21057512 in words is "twenty-one million, fifty-seven thousand, five hundred twelve".