666755747557666 has 16 divisors (see below), whose sum is σ = 1088170760094264. Its totient is φ = 304560912443904.

The previous prime is 666755747557663. The next prime is 666755747557693.

666755747557666 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in 4 ways, for example, as 529734184562025 + 137021562995641 = 23015955^2 + 11705621^2 .

It is not an unprimeable number, because it can be changed into a prime (666755747557663) 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, 132187893505 + ... + 132187898548.

Almost surely, 2^{666755747557666} is an apocalyptic number.

666755747557666 is a deficient number, since it is larger than the sum of its proper divisors (421415012536598).

666755747557666 is a wasteful number, since it uses less digits than its factorization.

666755747557666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264375792165.

The product of its digits is 280052640000, while the sum is 88.

The spelling of 666755747557666 in words is "six hundred sixty-six trillion, seven hundred fifty-five billion, seven hundred forty-seven million, five hundred fifty-seven thousand, six hundred sixty-six".