21321444 has 12 divisors (see below), whose sum is σ = 49750064. Its totient is φ = 7107144.

The previous prime is 21321431. The next prime is 21321449. The reversal of 21321444 is 44412312.

It is a tau number, because it is divible by the number of its divisors (12).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21321444.

It is not an unprimeable number, because it can be changed into a prime (21321449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 888382 + ... + 888405.

Almost surely, 2^21321444 is an apocalyptic number.

It is an amenable number.

21321444 is an abundant number, since it is smaller than the sum of its proper divisors (28428620).

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

21321444 is a wasteful number, since it uses less digits than its factorization.

21321444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1776794 (or 1776792 counting only the distinct ones).

The product of its digits is 768, while the sum is 21.

The square root of 21321444 is about 4617.5149160560. The cubic root of 21321444 is about 277.2929776452.

Adding to 21321444 its reverse (44412312), we get a palindrome (65733756).

The spelling of 21321444 in words is "twenty-one million, three hundred twenty-one thousand, four hundred forty-four".