81517 has 2 divisors, whose sum is σ = 81518. Its totient is φ = 81516.

The previous prime is 81509. The next prime is 81527. The reversal of 81517 is 71518.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45796 + 35721 = 214^2 + 189^2 .

It is a cyclic number.

It is not a de Polignac number, because 81517 - 2³ = 81509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81527) 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 as a sum of consecutive naturals, namely, 40758 + 40759.

It is an arithmetic number, because the mean of its divisors is an integer number (40759).

2⁸¹⁵¹⁷ is an apocalyptic number.

It is an amenable number.

81517 is a deficient number, since it is larger than the sum of its proper divisors (1).

81517 is an equidigital number, since it uses as much as digits as its factorization.

81517 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 280, while the sum is 22.

The square root of 81517 is about 285.5118211213. The cubic root of 81517 is about 43.3593466426.

Subtracting from 81517 its reverse (71518), we obtain a palindrome (9999).

The spelling of 81517 in words is "eighty-one thousand, five hundred seventeen".