21291304 has 8 divisors (see below), whose sum is σ = 39921210. Its totient is φ = 10645648.

The previous prime is 21291301. The next prime is 21291311. The reversal of 21291304 is 40319212.

It can be written as a sum of positive squares in only one way, i.e., 21252100 + 39204 = 4610^2 + 198^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (21291301) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1330699 + ... + 1330714.

Almost surely, 2^21291304 is an apocalyptic number.

It is an amenable number.

21291304 is a deficient number, since it is larger than the sum of its proper divisors (18629906).

21291304 is a wasteful number, since it uses less digits than its factorization.

21291304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2661419 (or 2661415 counting only the distinct ones).

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21291304 is about 4614.2501015875. The cubic root of 21291304 is about 277.1622555492.

The spelling of 21291304 in words is "twenty-one million, two hundred ninety-one thousand, three hundred four".