21957879173 has 4 divisors (see below), whose sum is σ = 22666197888. Its totient is φ = 21249560460.

The previous prime is 21957879149. The next prime is 21957879187. The reversal of 21957879173 is 37197875912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21957879173 - 2¹⁶ = 21957813637 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21957879103) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 354159311 + ... + 354159372.

It is an arithmetic number, because the mean of its divisors is an integer number (5666549472).

Almost surely, 2^21957879173 is an apocalyptic number.

It is an amenable number.

21957879173 is a deficient number, since it is larger than the sum of its proper divisors (708318715).

21957879173 is an equidigital number, since it uses as much as digits as its factorization.

21957879173 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 708318714.

The product of its digits is 6667920, while the sum is 59.

The spelling of 21957879173 in words is "twenty-one billion, nine hundred fifty-seven million, eight hundred seventy-nine thousand, one hundred seventy-three".