664817 has 4 divisors (see below), whose sum is σ = 667380. Its totient is φ = 662256.

The previous prime is 664799. The next prime is 664843. The reversal of 664817 is 718466.

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 323761 + 341056 = 569^2 + 584^2 .

It is a cyclic number.

It is not a de Polignac number, because 664817 - 2⁸ = 664561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664847) 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, 842 + ... + 1427.

It is an arithmetic number, because the mean of its divisors is an integer number (166845).

2⁶⁶⁴⁸¹⁷ is an apocalyptic number.

It is an amenable number.

664817 is a deficient number, since it is larger than the sum of its proper divisors (2563).

664817 is a wasteful number, since it uses less digits than its factorization.

664817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2562.

The product of its digits is 8064, while the sum is 32.

The square root of 664817 is about 815.3631092955. The cubic root of 664817 is about 87.2771800061.

The spelling of 664817 in words is "six hundred sixty-four thousand, eight hundred seventeen".