668136617 has 4 divisors (see below), whose sum is σ = 675643860. Its totient is φ = 660629376.

The previous prime is 668136613. The next prime is 668136629. The reversal of 668136617 is 716631866.

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 383337241 + 284799376 = 19579^2 + 16876^2 .

It is a cyclic number.

It is not a de Polignac number, because 668136617 - 2² = 668136613 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (668136611) 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 in 3 ways as a sum of consecutive naturals, for example, 3753488 + ... + 3753665.

It is an arithmetic number, because the mean of its divisors is an integer number (168910965).

Almost surely, 2^668136617 is an apocalyptic number.

It is an amenable number.

668136617 is a deficient number, since it is larger than the sum of its proper divisors (7507243).

668136617 is an equidigital number, since it uses as much as digits as its factorization.

668136617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7507242.

The product of its digits is 217728, while the sum is 44.

The square root of 668136617 is about 25848.3387667370. The cubic root of 668136617 is about 874.2220533631. Note that the first 3 decimals are identical.

The spelling of 668136617 in words is "six hundred sixty-eight million, one hundred thirty-six thousand, six hundred seventeen".