668257813 has 4 divisors (see below), whose sum is σ = 668372908. Its totient is φ = 668142720.

The previous prime is 668257789. The next prime is 668257831. The reversal of 668257813 is 318752866.

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 595018449 + 73239364 = 24393^2 + 8558^2 .

It is a cyclic number.

It is not a de Polignac number, because 668257813 - 2⁵ = 668257781 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 (668257313) 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, 48348 + ... + 60613.

It is an arithmetic number, because the mean of its divisors is an integer number (167093227).

Almost surely, 2^668257813 is an apocalyptic number.

It is an amenable number.

668257813 is a deficient number, since it is larger than the sum of its proper divisors (115095).

668257813 is a wasteful number, since it uses less digits than its factorization.

668257813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 115094.

The product of its digits is 483840, while the sum is 46.

The square root of 668257813 is about 25850.6830277268. The cubic root of 668257813 is about 874.2749097238.

The spelling of 668257813 in words is "six hundred sixty-eight million, two hundred fifty-seven thousand, eight hundred thirteen".