21613388 has 12 divisors (see below), whose sum is σ = 38096520. Its totient is φ = 10728672.

The previous prime is 21613379. The next prime is 21613421. The reversal of 21613388 is 88331612.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18881 + ... + 19992.

It is an arithmetic number, because the mean of its divisors is an integer number (3174710).

Almost surely, 2^21613388 is an apocalyptic number.

It is an amenable number.

21613388 is a deficient number, since it is larger than the sum of its proper divisors (16483132).

21613388 is a wasteful number, since it uses less digits than its factorization.

21613388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39016 (or 39014 counting only the distinct ones).

The product of its digits is 6912, while the sum is 32.

The square root of 21613388 is about 4649.0201118085. The cubic root of 21613388 is about 278.5528566436.

The spelling of 21613388 in words is "twenty-one million, six hundred thirteen thousand, three hundred eighty-eight".