78317991817 has 32 divisors (see below), whose sum is σ = 89423873280. Its totient is φ = 68041416960.

The previous prime is 78317991793. The next prime is 78317991833. The reversal of 78317991817 is 71819971387.

It is a cyclic number.

It is not a de Polignac number, because 78317991817 - 2¹¹ = 78317989769 is a prime.

It is a super-2 number, since 2×78317991817² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78317991847) 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 31 ways as a sum of consecutive naturals, for example, 24618967 + ... + 24622147.

It is an arithmetic number, because the mean of its divisors is an integer number (2794496040).

Almost surely, 2^78317991817 is an apocalyptic number.

It is an amenable number.

78317991817 is a deficient number, since it is larger than the sum of its proper divisors (11105881463).

78317991817 is a wasteful number, since it uses less digits than its factorization.

78317991817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4513.

The product of its digits is 5334336, while the sum is 61.

The spelling of 78317991817 in words is "seventy-eight billion, three hundred seventeen million, nine hundred ninety-one thousand, eight hundred seventeen".