81591232 has 28 divisors (see below), whose sum is σ = 162195256. Its totient is φ = 40723200.

The previous prime is 81591227. The next prime is 81591233. The reversal of 81591232 is 23219518.

It is a junction number, because it is equal to n+sod(n) for n = 81591194 and 81591203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81591233) 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, 66658 + ... + 67870.

Almost surely, 2^81591232 is an apocalyptic number.

It is an amenable number.

81591232 is a deficient number, since it is larger than the sum of its proper divisors (80604024).

81591232 is a wasteful number, since it uses less digits than its factorization.

81591232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2276 (or 2266 counting only the distinct ones).

The product of its digits is 4320, while the sum is 31.

The square root of 81591232 is about 9032.7865025140. The cubic root of 81591232 is about 433.7250412102.

The spelling of 81591232 in words is "eighty-one million, five hundred ninety-one thousand, two hundred thirty-two".