668309 has 4 divisors (see below), whose sum is σ = 672000. Its totient is φ = 664620.

The previous prime is 668303. The next prime is 668347. The reversal of 668309 is 903866.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 903866 = 2 ⋅451933.

It is a cyclic number.

It is not a de Polignac number, because 668309 - 2¹⁶ = 602773 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668303) 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, 1559 + ... + 1940.

It is an arithmetic number, because the mean of its divisors is an integer number (168000).

2⁶⁶⁸³⁰⁹ is an apocalyptic number.

It is an amenable number.

668309 is a deficient number, since it is larger than the sum of its proper divisors (3691).

668309 is a wasteful number, since it uses less digits than its factorization.

668309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3690.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 668309 is about 817.5016819555. The cubic root of 668309 is about 87.4297231631.

The spelling of 668309 in words is "six hundred sixty-eight thousand, three hundred nine".