666666657 has 12 divisors (see below), whose sum is σ = 969892560. Its totient is φ = 441246168.

The previous prime is 666666653. The next prime is 666666667. The reversal of 666666657 is 756666666.

It is a happy number.

666666657 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 666666657 - 2² = 666666653 is a prime.

It is not an unprimeable number, because it can be changed into a prime (666666653) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 265203 + ... + 267704.

It is an arithmetic number, because the mean of its divisors is an integer number (80824380).

Almost surely, 2^666666657 is an apocalyptic number.

It is an amenable number.

666666657 is a deficient number, since it is larger than the sum of its proper divisors (303225903).

666666657 is a wasteful number, since it uses less digits than its factorization.

666666657 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 533052 (or 533049 counting only the distinct ones).

The product of its digits is 9797760, while the sum is 54.

The square root of 666666657 is about 25819.8887875219. Note that the first 3 decimals coincide. The cubic root of 666666657 is about 873.5804605140.

Subtracting 666666657 from its reverse (756666666), we obtain a palindrome (90000009).

The spelling of 666666657 in words is "six hundred sixty-six million, six hundred sixty-six thousand, six hundred fifty-seven".