21135904 has 24 divisors (see below), whose sum is σ = 43802640. Its totient is φ = 10011456.

The previous prime is 21135901. The next prime is 21135911. The reversal of 21135904 is 40953112.

It is not an unprimeable number, because it can be changed into a prime (21135901) 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, 16774 + ... + 17989.

It is an arithmetic number, because the mean of its divisors is an integer number (1825110).

Almost surely, 2^21135904 is an apocalyptic number.

It is an amenable number.

21135904 is an abundant number, since it is smaller than the sum of its proper divisors (22666736).

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

21135904 is a wasteful number, since it uses less digits than its factorization.

21135904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34792 (or 34784 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 25.

The square root of 21135904 is about 4597.3801235051. The cubic root of 21135904 is about 276.4862952331.

The spelling of 21135904 in words is "twenty-one million, one hundred thirty-five thousand, nine hundred four".