666688348985 has 16 divisors (see below), whose sum is σ = 852481844496. Its totient is φ = 498779793408.

The previous prime is 666688348981. The next prime is 666688349021. The reversal of 666688348985 is 589843886666.

It can be written as a sum of positive squares in 8 ways, for example, as 4920741904 + 661767607081 = 70148^2 + 813491^2 .

It is a cyclic number.

It is not a de Polignac number, because 666688348985 - 2² = 666688348981 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666688348981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 24965612 + ... + 24992301.

It is an arithmetic number, because the mean of its divisors is an integer number (53280115281).

Almost surely, 2^666688348985 is an apocalyptic number.

It is an amenable number.

666688348985 is a deficient number, since it is larger than the sum of its proper divisors (185793495511).

666688348985 is a wasteful number, since it uses less digits than its factorization.

666688348985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49958092.

The product of its digits is 2866544640, while the sum is 77.

The spelling of 666688348985 in words is "six hundred sixty-six billion, six hundred eighty-eight million, three hundred forty-eight thousand, nine hundred eighty-five".