81797 has 4 divisors (see below), whose sum is σ = 82476. Its totient is φ = 81120.

The previous prime is 81773. The next prime is 81799. The reversal of 81797 is 79718.

It is a Cunningham number, because it is equal to 286²+1.

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 23716 + 58081 = 154^2 + 241^2 .

It is a cyclic number.

It is not a de Polignac number, because 81797 - 2¹⁴ = 65413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81799) 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, 104 + ... + 417.

It is an arithmetic number, because the mean of its divisors is an integer number (20619).

2⁸¹⁷⁹⁷ is an apocalyptic number.

It is an amenable number.

81797 is a deficient number, since it is larger than the sum of its proper divisors (679).

81797 is a wasteful number, since it uses less digits than its factorization.

81797 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678.

The product of its digits is 3528, while the sum is 32.

The square root of 81797 is about 286.0017482464. The cubic root of 81797 is about 43.4089344302.

It can be divided in two parts, 81 and 797, that added together give a palindrome (878).

The spelling of 81797 in words is "eighty-one thousand, seven hundred ninety-seven".