81365 has 4 divisors (see below), whose sum is σ = 97644. Its totient is φ = 65088.

The previous prime is 81359. The next prime is 81371. The reversal of 81365 is 56318.

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

It is an interprime number because it is at equal distance from previous prime (81359) and next prime (81371).

It can be written as a sum of positive squares in 2 ways, for example, as 58564 + 22801 = 242^2 + 151^2 .

It is a cyclic number.

It is not a de Polignac number, because 81365 - 2⁴ = 81349 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81365.

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 81365.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 8132 + ... + 8141.

It is an arithmetic number, because the mean of its divisors is an integer number (24411).

2⁸¹³⁶⁵ is an apocalyptic number.

It is an amenable number.

81365 is a deficient number, since it is larger than the sum of its proper divisors (16279).

81365 is a wasteful number, since it uses less digits than its factorization.

81365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16278.

The product of its digits is 720, while the sum is 23.

The square root of 81365 is about 285.2455082907. The cubic root of 81365 is about 43.3323799922.

It can be divided in two parts, 813 and 65, that added together give a palindrome (878).

The spelling of 81365 in words is "eighty-one thousand, three hundred sixty-five".