78765173849 has 2 divisors, whose sum is σ = 78765173850. Its totient is φ = 78765173848.

The previous prime is 78765173821. The next prime is 78765173939. The reversal of 78765173849 is 94837156787.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78152116249 + 613057600 = 279557^2 + 24760^2 .

It is an emirp because it is prime and its reverse (94837156787) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78765173849 - 2⁸ = 78765173593 is a prime.

It is a super-2 number, since 2×78765173849² (a number of 23 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (78765373849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39382586924 + 39382586925.

It is an arithmetic number, because the mean of its divisors is an integer number (39382586925).

Almost surely, 2^78765173849 is an apocalyptic number.

It is an amenable number.

78765173849 is a deficient number, since it is larger than the sum of its proper divisors (1).

78765173849 is an equidigital number, since it uses as much as digits as its factorization.

78765173849 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 71124480, while the sum is 65.

The spelling of 78765173849 in words is "seventy-eight billion, seven hundred sixty-five million, one hundred seventy-three thousand, eight hundred forty-nine".