78394603681 has 2 divisors, whose sum is σ = 78394603682. Its totient is φ = 78394603680.

The previous prime is 78394603663. The next prime is 78394603691. The reversal of 78394603681 is 18630649387.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 78388800400 + 5803281 = 279980^2 + 2409^2 .

It is a cyclic number.

It is not a de Polignac number, because 78394603681 - 2¹⁵ = 78394570913 is a prime.

It is a super-2 number, since 2×78394603681² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (78394603691) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 39197301840 + 39197301841.

It is an arithmetic number, because the mean of its divisors is an integer number (39197301841).

Almost surely, 2^78394603681 is an apocalyptic number.

It is an amenable number.

78394603681 is a deficient number, since it is larger than the sum of its proper divisors (1).

78394603681 is an equidigital number, since it uses as much as digits as its factorization.

78394603681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5225472, while the sum is 55.

The spelling of 78394603681 in words is "seventy-eight billion, three hundred ninety-four million, six hundred three thousand, six hundred eighty-one".