21665400719800 has 96 divisors (see below), whose sum is σ = 51862579488720. Its totient is φ = 8411872179200.

The previous prime is 21665400719693. The next prime is 21665400719869. The reversal of 21665400719800 is 891700456612.

It is a happy number.

It is a super-2 number, since 2×21665400719800² (a number of 27 digits) contains 22 as substring.

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, 5090494 + ... + 8321293.

Almost surely, 2^{21665400719800} is an apocalyptic number.

21665400719800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21665400719800 is an abundant number, since it is smaller than the sum of its proper divisors (30197178768920).

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

21665400719800 is a wasteful number, since it uses less digits than its factorization.

21665400719800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13412041 (or 13412032 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 49.

The spelling of 21665400719800 in words is "twenty-one trillion, six hundred sixty-five billion, four hundred million, seven hundred nineteen thousand, eight hundred".