668661791 has 12 divisors (see below), whose sum is σ = 783516528. Its totient is φ = 568949472.

The previous prime is 668661779. The next prime is 668661841. The reversal of 668661791 is 197166866.

It is not a de Polignac number, because 668661791 - 2²⁶ = 601552927 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668661761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 43091 + ... + 56516.

It is an arithmetic number, because the mean of its divisors is an integer number (65293044).

Almost surely, 2^668661791 is an apocalyptic number.

668661791 is a deficient number, since it is larger than the sum of its proper divisors (114854737).

668661791 is a wasteful number, since it uses less digits than its factorization.

668661791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99758 (or 99751 counting only the distinct ones).

The product of its digits is 653184, while the sum is 50.

The square root of 668661791 is about 25858.4955285492. The cubic root of 668661791 is about 874.4510476736.

The spelling of 668661791 in words is "six hundred sixty-eight million, six hundred sixty-one thousand, seven hundred ninety-one".