21393344 has 84 divisors (see below), whose sum is σ = 52358544. Its totient is φ = 8466432.

The previous prime is 21393313. The next prime is 21393367. The reversal of 21393344 is 44339312.

21393344 = T₁₅₂ + T₁₅₃ + ... + T₅₀₈.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 403622 + ... + 403674.

It is an arithmetic number, because the mean of its divisors is an integer number (623316).

Almost surely, 2^21393344 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 21393344, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26179272).

21393344 is an abundant number, since it is smaller than the sum of its proper divisors (30965200).

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

21393344 is an equidigital number, since it uses as much as digits as its factorization.

21393344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142 (or 79 counting only the distinct ones).

The product of its digits is 7776, while the sum is 29.

The square root of 21393344 is about 4625.2939366055. The cubic root of 21393344 is about 277.6043229761.

The spelling of 21393344 in words is "twenty-one million, three hundred ninety-three thousand, three hundred forty-four".