81231831 has 18 divisors (see below), whose sum is σ = 124646912. Its totient is φ = 50967360.

The previous prime is 81231823. The next prime is 81231841. The reversal of 81231831 is 13813218.

It is not a de Polignac number, because 81231831 - 2³ = 81231823 is a prime.

It is a super-2 number, since 2×81231831² = 13197220735225122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81231795 and 81231804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81231841) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 13015 + ... + 18216.

Almost surely, 2^81231831 is an apocalyptic number.

81231831 is a deficient number, since it is larger than the sum of its proper divisors (43415081).

81231831 is a wasteful number, since it uses less digits than its factorization.

81231831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31271 (or 31251 counting only the distinct ones).

The product of its digits is 1152, while the sum is 27.

The square root of 81231831 is about 9012.8702975245. The cubic root of 81231831 is about 433.0872657543.

The spelling of 81231831 in words is "eighty-one million, two hundred thirty-one thousand, eight hundred thirty-one".