666808013 has 4 divisors (see below), whose sum is σ = 667590588. Its totient is φ = 666025440.

The previous prime is 666808003. The next prime is 666808081. The reversal of 666808013 is 310808666.

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 91431844 + 575376169 = 9562^2 + 23987^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666808013 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 (666808003) 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, 390008 + ... + 391713.

It is an arithmetic number, because the mean of its divisors is an integer number (166897647).

Almost surely, 2^666808013 is an apocalyptic number.

It is an amenable number.

666808013 is a deficient number, since it is larger than the sum of its proper divisors (782575).

666808013 is an equidigital number, since it uses as much as digits as its factorization.

666808013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 782574.

The product of its (nonzero) digits is 41472, while the sum is 38.

The square root of 666808013 is about 25822.6259896239. The cubic root of 666808013 is about 873.6421990713.

The spelling of 666808013 in words is "six hundred sixty-six million, eight hundred eight thousand, thirteen".