664819191 has 8 divisors (see below), whose sum is σ = 984917360. Its totient is φ = 443212776.

The previous prime is 664819159. The next prime is 664819237. The reversal of 664819191 is 191918466.

It is not a de Polignac number, because 664819191 - 2⁵ = 664819159 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 (664819591) 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 7 ways as a sum of consecutive naturals, for example, 12311440 + ... + 12311493.

It is an arithmetic number, because the mean of its divisors is an integer number (123114670).

Almost surely, 2^664819191 is an apocalyptic number.

664819191 is a deficient number, since it is larger than the sum of its proper divisors (320098169).

664819191 is a wasteful number, since it uses less digits than its factorization.

664819191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24622942 (or 24622936 counting only the distinct ones).

The product of its digits is 93312, while the sum is 45.

The square root of 664819191 is about 25784.0879419847. The cubic root of 664819191 is about 872.7727588420.

The spelling of 664819191 in words is "six hundred sixty-four million, eight hundred nineteen thousand, one hundred ninety-one".