21957639157 has 4 divisors (see below), whose sum is σ = 21959666176. Its totient is φ = 21955612140.

The previous prime is 21957639091. The next prime is 21957639163. The reversal of 21957639157 is 75193675912.

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 21957639157 - 2²⁷ = 21823421429 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21957639098 and 21957639107.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21957639757) 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, 997173 + ... + 1018954.

It is an arithmetic number, because the mean of its divisors is an integer number (5489916544).

Almost surely, 2^21957639157 is an apocalyptic number.

It is an amenable number.

21957639157 is a deficient number, since it is larger than the sum of its proper divisors (2027019).

21957639157 is a wasteful number, since it uses less digits than its factorization.

21957639157 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2027018.

The product of its digits is 3572100, while the sum is 55.

The spelling of 21957639157 in words is "twenty-one billion, nine hundred fifty-seven million, six hundred thirty-nine thousand, one hundred fifty-seven".