81577864377 has 18 divisors (see below), whose sum is σ = 118520146862. Its totient is φ = 54070698816.

The previous prime is 81577864363. The next prime is 81577864393. The reversal of 81577864377 is 77346877518.

81577864377 is a `hidden beast` number, since 81 + 57 + 78 + 6 + 437 + 7 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 46226720016 + 35351144361 = 215004^2 + 188019^2 .

It is not a de Polignac number, because 81577864377 - 2³⁰ = 80504122553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81577864337) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 117933 + ... + 420789.

Almost surely, 2^81577864377 is an apocalyptic number.

It is an amenable number.

81577864377 is a deficient number, since it is larger than the sum of its proper divisors (36942282485).

81577864377 is a wasteful number, since it uses less digits than its factorization.

81577864377 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 303209 (or 303033 counting only the distinct ones).

The product of its digits is 55319040, while the sum is 63.

The spelling of 81577864377 in words is "eighty-one billion, five hundred seventy-seven million, eight hundred sixty-four thousand, three hundred seventy-seven".