21057618 has 16 divisors (see below), whose sum is σ = 43474176. Its totient is φ = 6792720.

The previous prime is 21057599. The next prime is 21057623. The reversal of 21057618 is 81675012.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 56421 + ... + 56792.

It is an arithmetic number, because the mean of its divisors is an integer number (2717136).

Almost surely, 2^21057618 is an apocalyptic number.

21057618 is an abundant number, since it is smaller than the sum of its proper divisors (22416558).

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

21057618 is a wasteful number, since it uses less digits than its factorization.

21057618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113249.

The product of its (nonzero) digits is 3360, while the sum is 30.

The square root of 21057618 is about 4588.8580278758. The cubic root of 21057618 is about 276.1445105441.

The spelling of 21057618 in words is "twenty-one million, fifty-seven thousand, six hundred eighteen".