666768043817 has 4 divisors (see below), whose sum is σ = 684788801796. Its totient is φ = 648747285840.

The previous prime is 666768043801. The next prime is 666768043847. The reversal of 666768043817 is 718340867666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 233230077721 + 433537966096 = 482939^2 + 658436^2 .

It is a cyclic number.

It is not a de Polignac number, because 666768043817 - 2⁴ = 666768043801 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666768043817.

It is not an unprimeable number, because it can be changed into a prime (666768043847) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9010378934 + ... + 9010379007.

It is an arithmetic number, because the mean of its divisors is an integer number (171197200449).

Almost surely, 2^666768043817 is an apocalyptic number.

It is an amenable number.

666768043817 is a deficient number, since it is larger than the sum of its proper divisors (18020757979).

666768043817 is a wasteful number, since it uses less digits than its factorization.

666768043817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18020757978.

The product of its (nonzero) digits is 48771072, while the sum is 62.

The spelling of 666768043817 in words is "six hundred sixty-six billion, seven hundred sixty-eight million, forty-three thousand, eight hundred seventeen".