131557818681 has 45 divisors (see below), whose sum is σ = 198499690389. Its totient is φ = 86832534600.

The previous prime is 131557818671. The next prime is 131557818701. The reversal of 131557818681 is 186818755131.

The square root of 131557818681 is 362709.

It is a perfect power (a square), and thus also a powerful number.

131557818681 is a `hidden beast` number, since 1 + 3 + 1 + 5 + 578 + 1 + 8 + 68 + 1 = 666.

It is not a de Polignac number, because 131557818681 - 2⁵ = 131557818649 is a prime.

It is a super-3 number, since 3×131557818681³ (a number of 34 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (131557818641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 623496666 + ... + 623496876.

Almost surely, 2^131557818681 is an apocalyptic number.

131557818681 is the 362709-th square number.

131557818681 is the 181355-th centered octagonal number.

It is an amenable number.

131557818681 is a deficient number, since it is larger than the sum of its proper divisors (66941871708).

131557818681 is an frugal number, since it uses more digits than its factorization.

131557818681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 816 (or 405 counting only the distinct ones).

The product of its digits is 1612800, while the sum is 54.

The spelling of 131557818681 in words is "one hundred thirty-one billion, five hundred fifty-seven million, eight hundred eighteen thousand, six hundred eighty-one".