666666666666646 has 16 divisors (see below), whose sum is σ = 1002709832583888. Its totient is φ = 332430107263200.

The previous prime is 666666666666643. The next prime is 666666666666647. The reversal of 666666666666646 is 646666666666666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666666666666643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13099741 + ... + 38793511.

It is an arithmetic number, because the mean of its divisors is an integer number (62669364536493).

Almost surely, 2^{666666666666646} is an apocalyptic number.

666666666666646 is a deficient number, since it is larger than the sum of its proper divisors (336043165917242).

666666666666646 is a wasteful number, since it uses less digits than its factorization.

666666666666646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25728927.

The product of its digits is 313456656384, while the sum is 88.

The spelling of 666666666666646 in words is "six hundred sixty-six trillion, six hundred sixty-six billion, six hundred sixty-six million, six hundred sixty-six thousand, six hundred forty-six".