21839744 has 32 divisors (see below), whose sum is σ = 43982400. Its totient is φ = 10801152.

The previous prime is 21839737. The next prime is 21839767. The reversal of 21839744 is 44793812.

It is a tau number, because it is divible by the number of its divisors (32).

It is a junction number, because it is equal to n+sod(n) for n = 21839698 and 21839707.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11537 + ... + 13295.

It is an arithmetic number, because the mean of its divisors is an integer number (1374450).

Almost surely, 2^21839744 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 21839744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21991200).

21839744 is an abundant number, since it is smaller than the sum of its proper divisors (22142656).

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

21839744 is an equidigital number, since it uses as much as digits as its factorization.

21839744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1870 (or 1858 counting only the distinct ones).

The product of its digits is 48384, while the sum is 38.

The square root of 21839744 is about 4673.3011886674. The cubic root of 21839744 is about 279.5219052151.

The spelling of 21839744 in words is "twenty-one million, eight hundred thirty-nine thousand, seven hundred forty-four".