21722624 has 160 divisors (see below), whose sum is σ = 58924800. Its totient is φ = 7741440.

The previous prime is 21722609. The next prime is 21722627. The reversal of 21722624 is 42622712.

Its product of digits (2688) is a multiple of the sum of its prime factors (84).

It is a junction number, because it is equal to n+sod(n) for n = 21722593 and 21722602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21722627) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 749042 + ... + 749070.

It is an arithmetic number, because the mean of its divisors is an integer number (368280).

Almost surely, 2^21722624 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 21722624, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29462400).

21722624 is an abundant number, since it is smaller than the sum of its proper divisors (37202176).

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

21722624 is a wasteful number, since it uses less digits than its factorization.

21722624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84 (or 68 counting only the distinct ones).

The product of its digits is 2688, while the sum is 26.

The square root of 21722624 is about 4660.7535871359. The cubic root of 21722624 is about 279.0213453006.

The spelling of 21722624 in words is "twenty-one million, seven hundred twenty-two thousand, six hundred twenty-four".