668191 has 4 divisors (see below), whose sum is σ = 678232. Its totient is φ = 658152.

The previous prime is 668179. The next prime is 668201. The reversal of 668191 is 191866.

It is a happy number.

668191 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 668191 - 2⁵ = 668159 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 (668111) 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, 4920 + ... + 5053.

It is an arithmetic number, because the mean of its divisors is an integer number (169558).

2⁶⁶⁸¹⁹¹ is an apocalyptic number.

668191 is a deficient number, since it is larger than the sum of its proper divisors (10041).

668191 is an equidigital number, since it uses as much as digits as its factorization.

668191 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10040.

The product of its digits is 2592, while the sum is 31.

The square root of 668191 is about 817.4295076641. The cubic root of 668191 is about 87.4245771830.

The spelling of 668191 in words is "six hundred sixty-eight thousand, one hundred ninety-one".