666195197 has 4 divisors (see below), whose sum is σ = 666555036. Its totient is φ = 665835360.

The previous prime is 666195191. The next prime is 666195199. The reversal of 666195197 is 791591666.

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 112487236 + 553707961 = 10606^2 + 23531^2 .

It is a cyclic number.

It is not a de Polignac number, because 666195197 - 2⁸ = 666194941 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 (666195191) 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 3 ways as a sum of consecutive naturals, for example, 177128 + ... + 180849.

It is an arithmetic number, because the mean of its divisors is an integer number (166638759).

Almost surely, 2^666195197 is an apocalyptic number.

It is an amenable number.

666195197 is a deficient number, since it is larger than the sum of its proper divisors (359839).

666195197 is a wasteful number, since it uses less digits than its factorization.

666195197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 359838.

The product of its digits is 612360, while the sum is 50.

The square root of 666195197 is about 25810.7573891198. The cubic root of 666195197 is about 873.3744828263.

The spelling of 666195197 in words is "six hundred sixty-six million, one hundred ninety-five thousand, one hundred ninety-seven".