668657823 has 16 divisors (see below), whose sum is σ = 939505920. Its totient is φ = 421842816.

The previous prime is 668657791. The next prime is 668657849. The reversal of 668657823 is 328756866.

It is not a de Polignac number, because 668657823 - 2⁵ = 668657791 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668657893) 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 15 ways as a sum of consecutive naturals, for example, 49686 + ... + 61692.

It is an arithmetic number, because the mean of its divisors is an integer number (58719120).

Almost surely, 2^668657823 is an apocalyptic number.

668657823 is a deficient number, since it is larger than the sum of its proper divisors (270848097).

668657823 is a wasteful number, since it uses less digits than its factorization.

668657823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13006.

The product of its digits is 2903040, while the sum is 51.

The square root of 668657823 is about 25858.4188031674. The cubic root of 668657823 is about 874.4493179358.

The spelling of 668657823 in words is "six hundred sixty-eight million, six hundred fifty-seven thousand, eight hundred twenty-three".