21204590 has 32 divisors (see below), whose sum is σ = 42615936. Its totient is φ = 7529760.

The previous prime is 21204587. The next prime is 21204607. The reversal of 21204590 is 9540212.

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 15 ways as a sum of consecutive naturals, for example, 2489 + ... + 6971.

It is an arithmetic number, because the mean of its divisors is an integer number (1331748).

Almost surely, 2^21204590 is an apocalyptic number.

21204590 is an abundant number, since it is smaller than the sum of its proper divisors (21411346).

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

21204590 is a wasteful number, since it uses less digits than its factorization.

21204590 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4544.

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21204590 is about 4604.8441884607. The cubic root of 21204590 is about 276.7854734015.

The spelling of 21204590 in words is "twenty-one million, two hundred four thousand, five hundred ninety".