81947930231 has 4 divisors (see below), whose sum is σ = 82792754352. Its totient is φ = 81103106112.

The previous prime is 81947930203. The next prime is 81947930269. The reversal of 81947930231 is 13203974918.

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

It is not a de Polignac number, because 81947930231 - 2⁶ = 81947930167 is a prime.

It is a super-2 number, since 2×81947930231² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81947930291) 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, 422411915 + ... + 422412108.

It is an arithmetic number, because the mean of its divisors is an integer number (20698188588).

Almost surely, 2^81947930231 is an apocalyptic number.

81947930231 is a deficient number, since it is larger than the sum of its proper divisors (844824121).

81947930231 is an equidigital number, since it uses as much as digits as its factorization.

81947930231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 844824120.

The product of its (nonzero) digits is 326592, while the sum is 47.

The spelling of 81947930231 in words is "eighty-one billion, nine hundred forty-seven million, nine hundred thirty thousand, two hundred thirty-one".