1666685717 has 2 divisors, whose sum is σ = 1666685718. Its totient is φ = 1666685716.

The previous prime is 1666685707. The next prime is 1666685743. The reversal of 1666685717 is 7175866661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 839202961 + 827482756 = 28969^2 + 28766^2 .

It is an emirp because it is prime and its reverse (7175866661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1666685717 - 2⁶ = 1666685653 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666685707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833342858 + 833342859.

It is an arithmetic number, because the mean of its divisors is an integer number (833342859).

Almost surely, 2^1666685717 is an apocalyptic number.

It is an amenable number.

1666685717 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666685717 is an equidigital number, since it uses as much as digits as its factorization.

1666685717 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2540160, while the sum is 53.

The square root of 1666685717 is about 40825.0623637001. The cubic root of 1666685717 is about 1185.6356188130.

The spelling of 1666685717 in words is "one billion, six hundred sixty-six million, six hundred eighty-five thousand, seven hundred seventeen".