21431804 has 12 divisors (see below), whose sum is σ = 37538424. Its totient is φ = 10706544.

The previous prime is 21431777. The next prime is 21431821. The reversal of 21431804 is 40813412.

It is a self number, because there is not a number n which added to its sum of digits gives 21431804.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6647 + ... + 9329.

It is an arithmetic number, because the mean of its divisors is an integer number (3128202).

Almost surely, 2^21431804 is an apocalyptic number.

It is an amenable number.

21431804 is a deficient number, since it is larger than the sum of its proper divisors (16106620).

21431804 is a wasteful number, since it uses less digits than its factorization.

21431804 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4684 (or 4682 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 21431804 is about 4629.4496433161. The cubic root of 21431804 is about 277.7705782786.

The spelling of 21431804 in words is "twenty-one million, four hundred thirty-one thousand, eight hundred four".