81321344312317 has 4 divisors (see below), whose sum is σ = 81322928679420. Its totient is φ = 81319759945216.

The previous prime is 81321344312297. The next prime is 81321344312323. The reversal of 81321344312317 is 71321344312318.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 77776630639236 + 3544713673081 = 8819106^2 + 1882741^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81321344312317 is a prime.

It is a super-2 number, since 2×81321344312317² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81321344312017) 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, 792106558 + ... + 792209215.

It is an arithmetic number, because the mean of its divisors is an integer number (20330732169855).

Almost surely, 2^{81321344312317} is an apocalyptic number.

It is an amenable number.

81321344312317 is a deficient number, since it is larger than the sum of its proper divisors (1584367103).

81321344312317 is a wasteful number, since it uses less digits than its factorization.

81321344312317 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1584367102.

The product of its digits is 290304, while the sum is 43.

Subtracting from 81321344312317 its reverse (71321344312318), we obtain a palindrome (9999999999999).

The spelling of 81321344312317 in words is "eighty-one trillion, three hundred twenty-one billion, three hundred forty-four million, three hundred twelve thousand, three hundred seventeen".