81331171 has 4 divisors (see below), whose sum is σ = 81818352. Its totient is φ = 80843992.

The previous prime is 81331157. The next prime is 81331177. The reversal of 81331171 is 17113318.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81331171 is a prime.

It is a super-2 number, since 2×81331171² = 13229518752462482, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81331177) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 243340 + ... + 243673.

It is an arithmetic number, because the mean of its divisors is an integer number (20454588).

Almost surely, 2^81331171 is an apocalyptic number.

81331171 is a deficient number, since it is larger than the sum of its proper divisors (487181).

81331171 is a wasteful number, since it uses less digits than its factorization.

81331171 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 487180.

The product of its digits is 504, while the sum is 25.

The square root of 81331171 is about 9018.3796216394. The cubic root of 81331171 is about 433.2637374753.

Adding to 81331171 its reverse (17113318), we get a palindrome (98444489).

The spelling of 81331171 in words is "eighty-one million, three hundred thirty-one thousand, one hundred seventy-one".