21978209818176 has 112 divisors (see below), whose sum is σ = 58532487968064. Its totient is φ = 7277986400256.

The previous prime is 21978209818151. The next prime is 21978209818189. The reversal of 21978209818176 is 67181890287912.

It is a super-3 number, since 3×21978209818176³ (a number of 41 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21978209818176.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 160388026 + ... + 160524998.

Almost surely, 2^{21978209818176} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21978209818176, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29266243984032).

21978209818176 is an abundant number, since it is smaller than the sum of its proper divisors (36554278149888).

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

21978209818176 is a wasteful number, since it uses less digits than its factorization.

21978209818176 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142468 (or 142458 counting only the distinct ones).

The product of its (nonzero) digits is 48771072, while the sum is 69.

The spelling of 21978209818176 in words is "twenty-one trillion, nine hundred seventy-eight billion, two hundred nine million, eight hundred eighteen thousand, one hundred seventy-six".