21613636 has 12 divisors (see below), whose sum is σ = 41262480. Its totient is φ = 9824360.

The previous prime is 21613619. The next prime is 21613639. The reversal of 21613636 is 63631612.

It is a super-2 number, since 2×21613636² = 934298522280992, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21613639) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 245566 + ... + 245653.

It is an arithmetic number, because the mean of its divisors is an integer number (3438540).

Almost surely, 2^21613636 is an apocalyptic number.

It is an amenable number.

21613636 is a deficient number, since it is larger than the sum of its proper divisors (19648844).

21613636 is a wasteful number, since it uses less digits than its factorization.

21613636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 491234 (or 491232 counting only the distinct ones).

The product of its digits is 3888, while the sum is 28.

The square root of 21613636 is about 4649.0467840193. The cubic root of 21613636 is about 278.5539220456.

The spelling of 21613636 in words is "twenty-one million, six hundred thirteen thousand, six hundred thirty-six".