21666645064120 has 96 divisors (see below), whose sum is σ = 56712040423200. Its totient is φ = 7428182399232.

The previous prime is 21666645064081. The next prime is 21666645064133. The reversal of 21666645064120 is 2146054666612.

It is a super-2 number, since 2×21666645064120² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

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, 39284826 + ... + 39832534.

It is an arithmetic number, because the mean of its divisors is an integer number (590750421075).

Almost surely, 2^{21666645064120} is an apocalyptic number.

21666645064120 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21666645064120 is an abundant number, since it is smaller than the sum of its proper divisors (35045395359080).

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

21666645064120 is a wasteful number, since it uses less digits than its factorization.

21666645064120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 567917 (or 567906 counting only the distinct ones).

The product of its (nonzero) digits is 2488320, while the sum is 49.

The spelling of 21666645064120 in words is "twenty-one trillion, six hundred sixty-six billion, six hundred forty-five million, sixty-four thousand, one hundred twenty".