66777777779 has 2 divisors, whose sum is σ = 66777777780. Its totient is φ = 66777777778.

The previous prime is 66777777761. The next prime is 66777777791. The reversal of 66777777779 is 97777777766.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66777777779 - 2²⁰ = 66776729203 is a prime.

It is a Sophie Germain prime.

It is a plaindrome in base 10.

It is not a weakly prime, because it can be changed into another prime (66777777179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33388888889 + 33388888890.

It is an arithmetic number, because the mean of its divisors is an integer number (33388888890).

Almost surely, 2^66777777779 is an apocalyptic number.

66777777779 is a deficient number, since it is larger than the sum of its proper divisors (1).

66777777779 is an equidigital number, since it uses as much as digits as its factorization.

66777777779 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1867795524, while the sum is 77.

The spelling of 66777777779 in words is "sixty-six billion, seven hundred seventy-seven million, seven hundred seventy-seven thousand, seven hundred seventy-nine".