21333444 has 48 divisors (see below), whose sum is σ = 56185920. Its totient is φ = 6240640.

The previous prime is 21333439. The next prime is 21333451. The reversal of 21333444 is 44433312.

It is a super-2 number, since 2×21333444² = 910231665802272, which contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1042 + ... + 6614.

It is an arithmetic number, because the mean of its divisors is an integer number (1170540).

Almost surely, 2^21333444 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 21333444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28092960).

21333444 is an abundant number, since it is smaller than the sum of its proper divisors (34852476).

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

21333444 is a wasteful number, since it uses less digits than its factorization.

21333444 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5620 (or 5618 counting only the distinct ones).

The product of its digits is 3456, while the sum is 24.

The square root of 21333444 is about 4618.8141335196. The cubic root of 21333444 is about 277.3449893143.

Adding to 21333444 its reverse (44433312), we get a palindrome (65766756).

The spelling of 21333444 in words is "twenty-one million, three hundred thirty-three thousand, four hundred forty-four".