21724544 has 32 divisors (see below), whose sum is σ = 43788600. Its totient is φ = 10734592.

The previous prime is 21724537. The next prime is 21724553. The reversal of 21724544 is 44542712.

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

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, 10439 + ... + 12345.

Almost surely, 2^21724544 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 21724544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21894300).

21724544 is an abundant number, since it is smaller than the sum of its proper divisors (22064056).

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

21724544 is an equidigital number, since it uses as much as digits as its factorization.

21724544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2010 (or 1998 counting only the distinct ones).

The product of its digits is 8960, while the sum is 29.

The square root of 21724544 is about 4660.9595578593. The cubic root of 21724544 is about 279.0295656887.

The spelling of 21724544 in words is "twenty-one million, seven hundred twenty-four thousand, five hundred forty-four".