78515138017 has 2 divisors, whose sum is σ = 78515138018. Its totient is φ = 78515138016.

The previous prime is 78515137913. The next prime is 78515138021. The reversal of 78515138017 is 71083151587.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 77315139136 + 1199998881 = 278056^2 + 34641^2 .

It is a cyclic number.

It is not a de Polignac number, because 78515138017 - 2³¹ = 76367654369 is a prime.

It is not a weakly prime, because it can be changed into another prime (78515138057) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39257569008 + 39257569009.

It is an arithmetic number, because the mean of its divisors is an integer number (39257569009).

Almost surely, 2^78515138017 is an apocalyptic number.

It is an amenable number.

78515138017 is a deficient number, since it is larger than the sum of its proper divisors (1).

78515138017 is an equidigital number, since it uses as much as digits as its factorization.

78515138017 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 235200, while the sum is 46.

The spelling of 78515138017 in words is "seventy-eight billion, five hundred fifteen million, one hundred thirty-eight thousand, seventeen".