21975618 has 24 divisors (see below), whose sum is σ = 51127632. Its totient is φ = 6278664.

The previous prime is 21975601. The next prime is 21975637. The reversal of 21975618 is 81657912.

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 11 ways as a sum of consecutive naturals, for example, 37080 + ... + 37667.

It is an arithmetic number, because the mean of its divisors is an integer number (2130318).

Almost surely, 2^21975618 is an apocalyptic number.

21975618 is an abundant number, since it is smaller than the sum of its proper divisors (29152014).

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

21975618 is a wasteful number, since it uses less digits than its factorization.

21975618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 74766 (or 74759 counting only the distinct ones).

The product of its digits is 30240, while the sum is 39.

The square root of 21975618 is about 4687.8159093548. The cubic root of 21975618 is about 280.1003806757.

The spelling of 21975618 in words is "twenty-one million, nine hundred seventy-five thousand, six hundred eighteen".