81731223 has 54 divisors (see below), whose sum is σ = 145495896. Its totient is φ = 43300224.

The previous prime is 81731203. The next prime is 81731239. The reversal of 81731223 is 32213718.

It is not a de Polignac number, because 81731223 - 2⁵ = 81731191 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81731203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 53 ways as a sum of consecutive naturals, for example, 1219836 + ... + 1219902.

Almost surely, 2^81731223 is an apocalyptic number.

81731223 is a deficient number, since it is larger than the sum of its proper divisors (63764673).

81731223 is a wasteful number, since it uses less digits than its factorization.

81731223 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181 (or 94 counting only the distinct ones).

The product of its digits is 2016, while the sum is 27.

The square root of 81731223 is about 9040.5322299077. The cubic root of 81731223 is about 433.9729555518.

The spelling of 81731223 in words is "eighty-one million, seven hundred thirty-one thousand, two hundred twenty-three".