21204544 has 28 divisors (see below), whose sum is σ = 43109388. Its totient is φ = 10342400.

The previous prime is 21204509. The next prime is 21204553. The reversal of 21204544 is 44540212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 3564544 + 17640000 = 1888^2 + 4200^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1417 + ... + 6664.

It is an arithmetic number, because the mean of its divisors is an integer number (1539621).

Almost surely, 2^21204544 is an apocalyptic number.

It is an amenable number.

21204544 is an abundant number, since it is smaller than the sum of its proper divisors (21904844).

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

21204544 is an equidigital number, since it uses as much as digits as its factorization.

21204544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8134 (or 8124 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 22.

The square root of 21204544 is about 4604.8391937178. The cubic root of 21204544 is about 276.7852732539.

Adding to 21204544 its reverse (44540212), we get a palindrome (65744756).

The spelling of 21204544 in words is "twenty-one million, two hundred four thousand, five hundred forty-four".