21991680000 has 720 divisors, whose sum is σ = 83818294560. Its totient is φ = 5541888000.

The previous prime is 21991679989. The next prime is 21991680019. The reversal of 21991680000 is 8619912.

It is a tau number, because it is divible by the number of its divisors (720).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 264959959 + ... + 264960041.

It is an arithmetic number, because the mean of its divisors is an integer number (116414298).

Almost surely, 2^21991680000 is an apocalyptic number.

21991680000 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 21991680000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41909147280).

21991680000 is an abundant number, since it is smaller than the sum of its proper divisors (61826614560).

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

21991680000 is an equidigital number, since it uses as much as digits as its factorization.

21991680000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154 (or 116 counting only the distinct ones).

The product of its (nonzero) digits is 7776, while the sum is 36.

The spelling of 21991680000 in words is "twenty-one billion, nine hundred ninety-one million, six hundred eighty thousand".