66777777790 has 16 divisors (see below), whose sum is σ = 121550563440. Its totient is φ = 26410985920.

The previous prime is 66777777779. The next prime is 66777777791. The reversal of 66777777790 is 9777777766.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66777777791) 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 in 7 ways as a sum of consecutive naturals, for example, 37514716 + ... + 37516495.

It is an arithmetic number, because the mean of its divisors is an integer number (7596910215).

Almost surely, 2^66777777790 is an apocalyptic number.

66777777790 is a deficient number, since it is larger than the sum of its proper divisors (54772785650).

66777777790 is a wasteful number, since it uses less digits than its factorization.

66777777790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 75031307.

The product of its (nonzero) digits is 266827932, while the sum is 70.

The spelling of 66777777790 in words is "sixty-six billion, seven hundred seventy-seven million, seven hundred seventy-seven thousand, seven hundred ninety".