78197365681 has 2 divisors, whose sum is σ = 78197365682. Its totient is φ = 78197365680.

The previous prime is 78197365633. The next prime is 78197365691. The reversal of 78197365681 is 18656379187.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 73557576225 + 4639789456 = 271215^2 + 68116^2 .

It is an emirp because it is prime and its reverse (18656379187) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 78197365681 - 2¹¹ = 78197363633 is a prime.

It is a super-2 number, since 2×78197365681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78197365621) 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 as a sum of consecutive naturals, namely, 39098682840 + 39098682841.

It is an arithmetic number, because the mean of its divisors is an integer number (39098682841).

Almost surely, 2^78197365681 is an apocalyptic number.

It is an amenable number.

78197365681 is a deficient number, since it is larger than the sum of its proper divisors (1).

78197365681 is an equidigital number, since it uses as much as digits as its factorization.

78197365681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15240960, while the sum is 61.

The spelling of 78197365681 in words is "seventy-eight billion, one hundred ninety-seven million, three hundred sixty-five thousand, six hundred eighty-one".