81673231 has 4 divisors (see below), whose sum is σ = 82015200. Its totient is φ = 81331264.

The previous prime is 81673223. The next prime is 81673279. The reversal of 81673231 is 13237618.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13237618 = 2 ⋅6618809.

It is a cyclic number.

It is not a de Polignac number, because 81673231 - 2³ = 81673223 is a prime.

It is a super-2 number, since 2×81673231² = 13341033323958722, 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 = 81673193 and 81673202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81673331) 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, 170626 + ... + 171103.

It is an arithmetic number, because the mean of its divisors is an integer number (20503800).

Almost surely, 2^81673231 is an apocalyptic number.

81673231 is a deficient number, since it is larger than the sum of its proper divisors (341969).

81673231 is a wasteful number, since it uses less digits than its factorization.

81673231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341968.

The product of its digits is 6048, while the sum is 31.

The square root of 81673231 is about 9037.3243274766. The cubic root of 81673231 is about 433.8702901182.

It can be divided in two parts, 816 and 73231, that added together give a palindrome (74047).

The spelling of 81673231 in words is "eighty-one million, six hundred seventy-three thousand, two hundred thirty-one".