81131874279 has 4 divisors (see below), whose sum is σ = 108175832376. Its totient is φ = 54087916184.

The previous prime is 81131874269. The next prime is 81131874287. The reversal of 81131874279 is 97247813118.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81131874279 - 2⁷ = 81131874151 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81131874269) 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, 13521979044 + ... + 13521979049.

It is an arithmetic number, because the mean of its divisors is an integer number (27043958094).

Almost surely, 2^81131874279 is an apocalyptic number.

81131874279 is a deficient number, since it is larger than the sum of its proper divisors (27043958097).

81131874279 is a wasteful number, since it uses less digits than its factorization.

81131874279 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27043958096.

The product of its digits is 677376, while the sum is 51.

The spelling of 81131874279 in words is "eighty-one billion, one hundred thirty-one million, eight hundred seventy-four thousand, two hundred seventy-nine".