21321344 has 64 divisors (see below), whose sum is σ = 48837600. Its totient is φ = 9169920.

The previous prime is 21321341. The next prime is 21321359. The reversal of 21321344 is 44312312.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (21321341) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26354 + ... + 27150.

Almost surely, 2^21321344 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 21321344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24418800).

21321344 is an abundant number, since it is smaller than the sum of its proper divisors (27516256).

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

21321344 is a wasteful number, since it uses less digits than its factorization.

21321344 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 841 (or 829 counting only the distinct ones).

The product of its digits is 576, while the sum is 20.

The square root of 21321344 is about 4617.5040877080. The cubic root of 21321344 is about 277.2925441327.

Adding to 21321344 its reverse (44312312), we get a palindrome (65633656).

The spelling of 21321344 in words is "twenty-one million, three hundred twenty-one thousand, three hundred forty-four".