6666578647 has 2 divisors, whose sum is σ = 6666578648. Its totient is φ = 6666578646.

The previous prime is 6666578617. The next prime is 6666578687. The reversal of 6666578647 is 7468756666.

It is a happy number.

6666578647 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 6666578647 - 2⁷ = 6666578519 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6666578617) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3333289323 + 3333289324.

It is an arithmetic number, because the mean of its divisors is an integer number (3333289324).

Almost surely, 2^6666578647 is an apocalyptic number.

6666578647 is a deficient number, since it is larger than the sum of its proper divisors (1).

6666578647 is an equidigital number, since it uses as much as digits as its factorization.

6666578647 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 60963840, while the sum is 61.

The square root of 6666578647 is about 81649.1190828168. The cubic root of 6666578647 is about 1882.0637747578.

The spelling of 6666578647 in words is "six billion, six hundred sixty-six million, five hundred seventy-eight thousand, six hundred forty-seven".