21049904 has 40 divisors (see below), whose sum is σ = 42131232. Its totient is φ = 10183680.

The previous prime is 21049883. The next prime is 21049907. The reversal of 21049904 is 40994012.

It is not an unprimeable number, because it can be changed into a prime (21049907) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87224 + ... + 87464.

Almost surely, 2^21049904 is an apocalyptic number.

It is an amenable number.

21049904 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

21049904 is a wasteful number, since it uses less digits than its factorization.

21049904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 405 (or 399 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 29.

The square root of 21049904 is about 4588.0174367585. The cubic root of 21049904 is about 276.1107865821.

The spelling of 21049904 in words is "twenty-one million, forty-nine thousand, nine hundred four".