78105378817 has 2 divisors, whose sum is σ = 78105378818. Its totient is φ = 78105378816.

The previous prime is 78105378781. The next prime is 78105378853. The reversal of 78105378817 is 71887350187.

Together with previous prime (78105378781) it forms an Ormiston pair, because they use the same digits, order apart.

It is a balanced prime because it is at equal distance from previous prime (78105378781) and next prime (78105378853).

It can be written as a sum of positive squares in only one way, i.e., 65520128961 + 12585249856 = 255969^2 + 112184^2 .

It is an emirp because it is prime and its reverse (71887350187) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78105378817 - 2²⁷ = 77971161089 is a prime.

It is a super-2 number, since 2×78105378817² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78105378877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39052689408 + 39052689409.

It is an arithmetic number, because the mean of its divisors is an integer number (39052689409).

Almost surely, 2^78105378817 is an apocalyptic number.

It is an amenable number.

78105378817 is a deficient number, since it is larger than the sum of its proper divisors (1).

78105378817 is an equidigital number, since it uses as much as digits as its factorization.

78105378817 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2634240, while the sum is 55.

The spelling of 78105378817 in words is "seventy-eight billion, one hundred five million, three hundred seventy-eight thousand, eight hundred seventeen".