778618989816881 has 2 divisors, whose sum is σ = 778618989816882. Its totient is φ = 778618989816880.

The previous prime is 778618989816821. The next prime is 778618989816887. The reversal of 778618989816881 is 188618989816877.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 553784439390625 + 224834550426256 = 23532625^2 + 14994484^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-778618989816881 is a prime.

It is a super-2 number, since 2×778618989816881² (a number of 31 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (778618989816887) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 389309494908440 + 389309494908441.

It is an arithmetic number, because the mean of its divisors is an integer number (389309494908441).

Almost surely, 2^{778618989816881} is an apocalyptic number.

It is an amenable number.

778618989816881 is a deficient number, since it is larger than the sum of its proper divisors (1).

778618989816881 is an equidigital number, since it uses as much as digits as its factorization.

778618989816881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 37456183296, while the sum is 95.

The spelling of 778618989816881 in words is "seven hundred seventy-eight trillion, six hundred eighteen billion, nine hundred eighty-nine million, eight hundred sixteen thousand, eight hundred eighty-one".