21117695957 has 8 divisors (see below), whose sum is σ = 21485139000. Its totient is φ = 20750938560.

The previous prime is 21117695933. The next prime is 21117696013. The reversal of 21117695957 is 75959671112.

It can be written as a sum of positive squares in 4 ways, for example, as 7349521 + 21110346436 = 2711^2 + 145294^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21117695957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21117695899 and 21117695908.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21117695917) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 109082 + ... + 232667.

It is an arithmetic number, because the mean of its divisors is an integer number (2685642375).

Almost surely, 2^21117695957 is an apocalyptic number.

It is an amenable number.

21117695957 is a deficient number, since it is larger than the sum of its proper divisors (367443043).

21117695957 is a wasteful number, since it uses less digits than its factorization.

21117695957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 342823.

The product of its digits is 1190700, while the sum is 53.

The spelling of 21117695957 in words is "twenty-one billion, one hundred seventeen million, six hundred ninety-five thousand, nine hundred fifty-seven".