21120081920 has 336 divisors, whose sum is σ = 62529323760. Its totient is φ = 6804209664.

The previous prime is 21120081907. The next prime is 21120081947. The reversal of 21120081920 is 2918002112.

It is a self number, because there is not a number n which added to its sum of digits gives 21120081920.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 34119371 + ... + 34119989.

Almost surely, 2^21120081920 is an apocalyptic number.

21120081920 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 21120081920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31264661880).

21120081920 is an abundant number, since it is smaller than the sum of its proper divisors (41409241840).

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

21120081920 is an equidigital number, since it uses as much as digits as its factorization.

21120081920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 681 (or 650 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 26.

The spelling of 21120081920 in words is "twenty-one billion, one hundred twenty million, eighty-one thousand, nine hundred twenty".