21304872 has 24 divisors (see below), whose sum is σ = 57700890. Its totient is φ = 7101600.

The previous prime is 21304867. The next prime is 21304873. The reversal of 21304872 is 27840312.

It can be written as a sum of positive squares in only one way, i.e., 21288996 + 15876 = 4614^2 + 126^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is not an unprimeable number, because it can be changed into a prime (21304873) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 147879 + ... + 148022.

Almost surely, 2^21304872 is an apocalyptic number.

It is an amenable number.

21304872 is an abundant number, since it is smaller than the sum of its proper divisors (36396018).

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

21304872 is a wasteful number, since it uses less digits than its factorization.

21304872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295913 (or 295906 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21304872 is about 4615.7200954997. The cubic root of 21304872 is about 277.2211174357.

The spelling of 21304872 in words is "twenty-one million, three hundred four thousand, eight hundred seventy-two".