664291 has 4 divisors (see below), whose sum is σ = 666000. Its totient is φ = 662584.

The previous prime is 664289. The next prime is 664319. The reversal of 664291 is 192466.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 192466 = 2 ⋅96233.

It is a cyclic number.

It is not a de Polignac number, because 664291 - 2¹ = 664289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664211) 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, 45 + ... + 1153.

It is an arithmetic number, because the mean of its divisors is an integer number (166500).

2⁶⁶⁴²⁹¹ is an apocalyptic number.

664291 is a deficient number, since it is larger than the sum of its proper divisors (1709).

664291 is a wasteful number, since it uses less digits than its factorization.

664291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1708.

The product of its digits is 2592, while the sum is 28.

The square root of 664291 is about 815.0404897918. The cubic root of 664291 is about 87.2541561718.

It can be divided in two parts, 66429 and 1, that added together give a triangular number (66430 = T₃₆₄).

The spelling of 664291 in words is "six hundred sixty-four thousand, two hundred ninety-one".