21222880 has 72 divisors (see below), whose sum is σ = 58346568. Its totient is φ = 7273728.

The previous prime is 21222847. The next prime is 21222913. The reversal of 21222880 is 8822212.

It is an interprime number because it is at equal distance from previous prime (21222847) and next prime (21222913).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6487 + ... + 9193.

It is an arithmetic number, because the mean of its divisors is an integer number (810369).

Almost surely, 2^21222880 is an apocalyptic number.

21222880 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 21222880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29173284).

21222880 is an abundant number, since it is smaller than the sum of its proper divisors (37123688).

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

21222880 is a wasteful number, since it uses less digits than its factorization.

21222880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2736 (or 2721 counting only the distinct ones).

The product of its (nonzero) digits is 1024, while the sum is 25.

The square root of 21222880 is about 4606.8297125029. The cubic root of 21222880 is about 276.8650308854.

The spelling of 21222880 in words is "twenty-one million, two hundred twenty-two thousand, eight hundred eighty".