21455997960 has 32 divisors (see below), whose sum is σ = 64367994240. Its totient is φ = 5721599424.

The previous prime is 21455997929. The next prime is 21455997961. The reversal of 21455997960 is 6979955412.

It is a self number, because there is not a number n which added to its sum of digits gives 21455997960.

It is not an unprimeable number, because it can be changed into a prime (21455997961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 89399872 + ... + 89400111.

It is an arithmetic number, because the mean of its divisors is an integer number (2011499820).

Almost surely, 2^21455997960 is an apocalyptic number.

21455997960 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21455997960 is an abundant number, since it is smaller than the sum of its proper divisors (42911996280).

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

21455997960 is a wasteful number, since it uses less digits than its factorization.

21455997960 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178799997 (or 178799993 counting only the distinct ones).

The product of its (nonzero) digits is 6123600, while the sum is 57.

The spelling of 21455997960 in words is "twenty-one billion, four hundred fifty-five million, nine hundred ninety-seven thousand, nine hundred sixty".