664191 has 12 divisors (see below), whose sum is σ = 1046760. Its totient is φ = 402480.

The previous prime is 664177. The next prime is 664193. The reversal of 664191 is 191466.

It is not a de Polignac number, because 664191 - 2¹⁰ = 663167 is a prime.

It is a super-2 number, since 2×664191² = 882299368962, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

664191 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (664193) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3256 + ... + 3453.

It is an arithmetic number, because the mean of its divisors is an integer number (87230).

2⁶⁶⁴¹⁹¹ is an apocalyptic number.

664191 is a deficient number, since it is larger than the sum of its proper divisors (382569).

664191 is a wasteful number, since it uses less digits than its factorization.

664191 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6726 (or 6723 counting only the distinct ones).

The product of its digits is 1296, while the sum is 27.

The square root of 664191 is about 814.9791408374. The cubic root of 664191 is about 87.2497776422.

The spelling of 664191 in words is "six hundred sixty-four thousand, one hundred ninety-one".