664865 has 8 divisors (see below), whose sum is σ = 806208. Its totient is φ = 526320.

The previous prime is 664849. The next prime is 664879. The reversal of 664865 is 568466.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 664865 - 2⁴ = 664849 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 131 + ... + 1160.

It is an arithmetic number, because the mean of its divisors is an integer number (100776).

2⁶⁶⁴⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

664865 is a deficient number, since it is larger than the sum of its proper divisors (141343).

664865 is a wasteful number, since it uses less digits than its factorization.

664865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1399.

The product of its digits is 34560, while the sum is 35.

The square root of 664865 is about 815.3925435028. The cubic root of 664865 is about 87.2792804357.

The spelling of 664865 in words is "six hundred sixty-four thousand, eight hundred sixty-five".