21320880 has 200 divisors, whose sum is σ = 79189872. Its totient is φ = 4741632.

The previous prime is 21320879. The next prime is 21320881. The reversal of 21320880 is 8802312.

It is an interprime number because it is at equal distance from previous prime (21320879) and next prime (21320881).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a self number, because there is not a number n which added to its sum of digits gives 21320880.

It is not an unprimeable number, because it can be changed into a prime (21320881) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 576222 + ... + 576258.

Almost surely, 2^21320880 is an apocalyptic number.

21320880 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 21320880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (39594936).

21320880 is an abundant number, since it is smaller than the sum of its proper divisors (57868992).

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

21320880 is an equidigital number, since it uses as much as digits as its factorization.

21320880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81 (or 54 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 24.

The square root of 21320880 is about 4617.4538438408. The cubic root of 21320880 is about 277.2905326167.

The spelling of 21320880 in words is "twenty-one million, three hundred twenty thousand, eight hundred eighty".