21726320 has 80 divisors (see below), whose sum is σ = 62995968. Its totient is φ = 6769920.

The previous prime is 21726317. The next prime is 21726349. The reversal of 21726320 is 2362712.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

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, 4397 + ... + 7923.

Almost surely, 2^21726320 is an apocalyptic number.

21726320 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21726320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31497984).

21726320 is an abundant number, since it is smaller than the sum of its proper divisors (41269648).

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

21726320 is a wasteful number, since it uses less digits than its factorization.

21726320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3558 (or 3552 counting only the distinct ones).

The product of its (nonzero) digits is 1008, while the sum is 23.

The square root of 21726320 is about 4661.1500726752. The cubic root of 21726320 is about 279.0371691165.

The spelling of 21726320 in words is "twenty-one million, seven hundred twenty-six thousand, three hundred twenty".