664187191 has 2 divisors, whose sum is σ = 664187192. Its totient is φ = 664187190.

The previous prime is 664187171. The next prime is 664187201. The reversal of 664187191 is 191781466.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 664187191 - 2¹⁵ = 664154423 is a prime.

It is a super-2 number, since 2×664187191² = 882289249376940962, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (664187171) 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 as a sum of consecutive naturals, namely, 332093595 + 332093596.

It is an arithmetic number, because the mean of its divisors is an integer number (332093596).

Almost surely, 2^664187191 is an apocalyptic number.

664187191 is a deficient number, since it is larger than the sum of its proper divisors (1).

664187191 is an equidigital number, since it uses as much as digits as its factorization.

664187191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 43.

The square root of 664187191 is about 25771.8294073199. The cubic root of 664187191 is about 872.4961085532.

The spelling of 664187191 in words is "six hundred sixty-four million, one hundred eighty-seven thousand, one hundred ninety-one".