778197979891 has 2 divisors, whose sum is σ = 778197979892. Its totient is φ = 778197979890.

The previous prime is 778197979861. The next prime is 778197979927. The reversal of 778197979891 is 198979791877.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 778197979891 - 2¹⁷ = 778197848819 is a prime.

It is not a weakly prime, because it can be changed into another prime (778197979861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 389098989945 + 389098989946.

It is an arithmetic number, because the mean of its divisors is an integer number (389098989946).

Almost surely, 2^778197979891 is an apocalyptic number.

778197979891 is a deficient number, since it is larger than the sum of its proper divisors (1).

778197979891 is an equidigital number, since it uses as much as digits as its factorization.

778197979891 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1008189504, while the sum is 82.

The spelling of 778197979891 in words is "seven hundred seventy-eight billion, one hundred ninety-seven million, nine hundred seventy-nine thousand, eight hundred ninety-one".