81131673813 has 8 divisors (see below), whose sum is σ = 108259884768. Its totient is φ = 54045622704.

The previous prime is 81131673797. The next prime is 81131673841. The reversal of 81131673813 is 31837613118.

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

It is not a de Polignac number, because 81131673813 - 2⁴ = 81131673797 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81131673113) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10535470 + ... + 10543167.

It is an arithmetic number, because the mean of its divisors is an integer number (13532485596).

Almost surely, 2^81131673813 is an apocalyptic number.

It is an amenable number.

81131673813 is a deficient number, since it is larger than the sum of its proper divisors (27128210955).

81131673813 is a wasteful number, since it uses less digits than its factorization.

81131673813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21079923.

The product of its digits is 72576, while the sum is 42.

The spelling of 81131673813 in words is "eighty-one billion, one hundred thirty-one million, six hundred seventy-three thousand, eight hundred thirteen".