81231 has 4 divisors (see below), whose sum is σ = 108312. Its totient is φ = 54152.

The previous prime is 81223. The next prime is 81233. The reversal of 81231 is 13218.

It is a happy number.

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 81231 - 2³ = 81223 is a prime.

It is a super-2 number, since 2×81231² = 13196950722, which contains 22 as substring.

It is a D-number.

It is a self number, because there is not a number n which added to its sum of digits gives 81231.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81233) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13536 + ... + 13541.

It is an arithmetic number, because the mean of its divisors is an integer number (27078).

2⁸¹²³¹ is an apocalyptic number.

81231 is a deficient number, since it is larger than the sum of its proper divisors (27081).

81231 is a wasteful number, since it uses less digits than its factorization.

81231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27080.

The product of its digits is 48, while the sum is 15.

The square root of 81231 is about 285.0105261214. The cubic root of 81231 is about 43.3085788925.

Adding to 81231 its reverse (13218), we get a palindrome (94449).

The spelling of 81231 in words is "eighty-one thousand, two hundred thirty-one".