21204344 has 64 divisors (see below), whose sum is σ = 48176640. Its totient is φ = 8553600.

The previous prime is 21204329. The next prime is 21204347. The reversal of 21204344 is 44340212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21204347) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 130007 + ... + 130169.

It is an arithmetic number, because the mean of its divisors is an integer number (752760).

Almost surely, 2^21204344 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21204344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24088320).

21204344 is an abundant number, since it is smaller than the sum of its proper divisors (26972296).

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

21204344 is a wasteful number, since it uses less digits than its factorization.

21204344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 300 (or 296 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 21204344 is about 4604.8174773817. The cubic root of 21204344 is about 276.7844030438.

Adding to 21204344 its reverse (44340212), we get a palindrome (65544556).

The spelling of 21204344 in words is "twenty-one million, two hundred four thousand, three hundred forty-four".