8157697913521 has 16 divisors (see below), whose sum is σ = 8983286064144. Its totient is φ = 7361431743744.

The previous prime is 8157697913461. The next prime is 8157697913557. The reversal of 8157697913521 is 1253197967518.

It can be written as a sum of positive squares in 8 ways, for example, as 1186835936400 + 6970861977121 = 1089420^2 + 2640239^2 .

It is not a de Polignac number, because 8157697913521 - 2⁹ = 8157697913009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8157697413521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21180826 + ... + 21562531.

It is an arithmetic number, because the mean of its divisors is an integer number (561455379009).

Almost surely, 2^{8157697913521} is an apocalyptic number.

It is an amenable number.

8157697913521 is a deficient number, since it is larger than the sum of its proper divisors (825588150623).

8157697913521 is a wasteful number, since it uses less digits than its factorization.

8157697913521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42743700.

The product of its digits is 28576800, while the sum is 64.

The spelling of 8157697913521 in words is "eight trillion, one hundred fifty-seven billion, six hundred ninety-seven million, nine hundred thirteen thousand, five hundred twenty-one".