665309 has 4 divisors (see below), whose sum is σ = 677916. Its totient is φ = 652704.

The previous prime is 665303. The next prime is 665311. The reversal of 665309 is 903566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 903566 = 2 ⋅451783.

It can be written as a sum of positive squares in 2 ways, for example, as 605284 + 60025 = 778^2 + 245^2 .

It is a cyclic number.

It is not a de Polignac number, because 665309 - 2⁴ = 665293 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 (665303) 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 3 ways as a sum of consecutive naturals, for example, 6224 + ... + 6329.

It is an arithmetic number, because the mean of its divisors is an integer number (169479).

2⁶⁶⁵³⁰⁹ is an apocalyptic number.

It is an amenable number.

665309 is a deficient number, since it is larger than the sum of its proper divisors (12607).

665309 is a wasteful number, since it uses less digits than its factorization.

665309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12606.

The product of its (nonzero) digits is 4860, while the sum is 29.

The square root of 665309 is about 815.6647595673. The cubic root of 665309 is about 87.2987046183.

The spelling of 665309 in words is "six hundred sixty-five thousand, three hundred nine".