21867904 has 16 divisors (see below), whose sum is σ = 43565220. Its totient is φ = 10933888.

The previous prime is 21867869. The next prime is 21867913. The reversal of 21867904 is 40976812.

It is a tau number, because it is divible by the number of its divisors (16).

It is a Smith number, since the sum of its digits (37) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 85294 + ... + 85549.

Almost surely, 2^21867904 is an apocalyptic number.

It is an amenable number.

21867904 is a deficient number, since it is larger than the sum of its proper divisors (21697316).

21867904 is an equidigital number, since it uses as much as digits as its factorization.

21867904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 170857 (or 170845 counting only the distinct ones).

The product of its (nonzero) digits is 24192, while the sum is 37.

The square root of 21867904 is about 4676.3130776286. The cubic root of 21867904 is about 279.6419914242.

The spelling of 21867904 in words is "twenty-one million, eight hundred sixty-seven thousand, nine hundred four".