81317 has 4 divisors (see below), whose sum is σ = 81900. Its totient is φ = 80736.

The previous prime is 81307. The next prime is 81331. The reversal of 81317 is 71318.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 37636 + 43681 = 194^2 + 209^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81317 is a prime.

It is a super-2 number, since 2×81317² = 13224908978, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 81317.

It is not an unprimeable number, because it can be changed into a prime (81307) 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, 59 + ... + 407.

It is an arithmetic number, because the mean of its divisors is an integer number (20475).

2⁸¹³¹⁷ is an apocalyptic number.

81317 is the 233-rd pentagonal number.

It is an amenable number.

81317 is a deficient number, since it is larger than the sum of its proper divisors (583).

81317 is a wasteful number, since it uses less digits than its factorization.

81317 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 582.

The product of its digits is 168, while the sum is 20.

The square root of 81317 is about 285.1613578310. The cubic root of 81317 is about 43.3238572310.

Subtracting from 81317 its reverse (71318), we obtain a palindrome (9999).

The spelling of 81317 in words is "eighty-one thousand, three hundred seventeen".