21618572 has 24 divisors (see below), whose sum is σ = 39357360. Its totient is φ = 10377920.

The previous prime is 21618533. The next prime is 21618581. The reversal of 21618572 is 27581612.

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, 25922 + ... + 26742.

It is an arithmetic number, because the mean of its divisors is an integer number (1639890).

Almost surely, 2^21618572 is an apocalyptic number.

It is an amenable number.

21618572 is a deficient number, since it is larger than the sum of its proper divisors (17738788).

21618572 is a wasteful number, since it uses less digits than its factorization.

21618572 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1081 (or 1079 counting only the distinct ones).

The product of its digits is 6720, while the sum is 32.

The square root of 21618572 is about 4649.5776152248. The cubic root of 21618572 is about 278.5751252883.

The spelling of 21618572 in words is "twenty-one million, six hundred eighteen thousand, five hundred seventy-two".