81715056613 has 4 divisors (see below), whose sum is σ = 83256850188. Its totient is φ = 80173263040.

The previous prime is 81715056571. The next prime is 81715056623. The reversal of 81715056613 is 31665051718.

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 35301524769 + 46413531844 = 187887^2 + 215438^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81715056613 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 81715056613.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81715056623) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 770896708 + ... + 770896813.

It is an arithmetic number, because the mean of its divisors is an integer number (20814212547).

Almost surely, 2^81715056613 is an apocalyptic number.

It is an amenable number.

81715056613 is a deficient number, since it is larger than the sum of its proper divisors (1541793575).

81715056613 is a wasteful number, since it uses less digits than its factorization.

81715056613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1541793574.

The product of its (nonzero) digits is 151200, while the sum is 43.

The spelling of 81715056613 in words is "eighty-one billion, seven hundred fifteen million, fifty-six thousand, six hundred thirteen".