666776777 has 2 divisors, whose sum is σ = 666776778. Its totient is φ = 666776776.

The previous prime is 666776743. The next prime is 666776819. The reversal of 666776777 is 777677666.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 652495936 + 14280841 = 25544^2 + 3779^2 .

It is a cyclic number.

It is not a de Polignac number, because 666776777 - 2⁶ = 666776713 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (666776707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333388388 + 333388389.

It is an arithmetic number, because the mean of its divisors is an integer number (333388389).

Almost surely, 2^666776777 is an apocalyptic number.

It is an amenable number.

666776777 is a deficient number, since it is larger than the sum of its proper divisors (1).

666776777 is an equidigital number, since it uses as much as digits as its factorization.

666776777 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 21781872, while the sum is 59.

The square root of 666776777 is about 25822.0211641149. The cubic root of 666776777 is about 873.6285572067.

The spelling of 666776777 in words is "six hundred sixty-six million, seven hundred seventy-six thousand, seven hundred seventy-seven".