21722880 has 72 divisors (see below), whose sum is σ = 69389712. Its totient is φ = 5791744.

The previous prime is 21722873. The next prime is 21722887. The reversal of 21722880 is 8822712.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21722873) and next prime (21722887).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21722887) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1012 + ... + 6668.

It is an arithmetic number, because the mean of its divisors is an integer number (963746).

Almost surely, 2^21722880 is an apocalyptic number.

21722880 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 21722880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34694856).

21722880 is an abundant number, since it is smaller than the sum of its proper divisors (47666832).

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

21722880 is an equidigital number, since it uses as much as digits as its factorization.

21722880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5681 (or 5667 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 21722880 is about 4660.7810504249. The cubic root of 21722880 is about 279.0224413803.

The spelling of 21722880 in words is "twenty-one million, seven hundred twenty-two thousand, eight hundred eighty".