21304904 has 24 divisors (see below), whose sum is σ = 40707030. Its totient is φ = 10451520.

The previous prime is 21304897. The next prime is 21304919. The reversal of 21304904 is 40940312.

It can be written as a sum of positive squares in only one way, i.e., 17656804 + 3648100 = 4202^2 + 1910^2 .

It is a hoax number, since the sum of its digits (23) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 21304904.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 111449 + ... + 111639.

Almost surely, 2^21304904 is an apocalyptic number.

It is an amenable number.

21304904 is a deficient number, since it is larger than the sum of its proper divisors (19402126).

21304904 is an equidigital number, since it uses as much as digits as its factorization.

21304904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 461 (or 266 counting only the distinct ones).

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21304904 is about 4615.7235619131. The cubic root of 21304904 is about 277.2212562314.

The spelling of 21304904 in words is "twenty-one million, three hundred four thousand, nine hundred four".