21518880 has 96 divisors (see below), whose sum is σ = 68511744. Its totient is φ = 5677056.

The previous prime is 21518879. The next prime is 21518881. The reversal of 21518880 is 8881512.

It is an interprime number because it is at equal distance from previous prime (21518879) and next prime (21518881).

It is a tau number, because it is divible by the number of its divisors (96).

It is not an unprimeable number, because it can be changed into a prime (21518881) 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, 60784 + ... + 61136.

It is an arithmetic number, because the mean of its divisors is an integer number (713664).

Almost surely, 2^21518880 is an apocalyptic number.

21518880 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 21518880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34255872).

21518880 is an abundant number, since it is smaller than the sum of its proper divisors (46992864).

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

21518880 is a wasteful number, since it uses less digits than its factorization.

21518880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 498 (or 490 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 33.

The square root of 21518880 is about 4638.8446837548. The cubic root of 21518880 is about 278.1462577700.

The spelling of 21518880 in words is "twenty-one million, five hundred eighteen thousand, eight hundred eighty".