668839 has 4 divisors (see below), whose sum is σ = 672400. Its totient is φ = 665280.

The previous prime is 668821. The next prime is 668851. The reversal of 668839 is 938866.

668839 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 668839 - 2¹⁵ = 636071 is a prime.

It is a Duffinian number.

668839 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (668869) 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, 1482 + ... + 1879.

It is an arithmetic number, because the mean of its divisors is an integer number (168100).

2⁶⁶⁸⁸³⁹ is an apocalyptic number.

668839 is a deficient number, since it is larger than the sum of its proper divisors (3561).

668839 is a wasteful number, since it uses less digits than its factorization.

668839 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3560.

The product of its digits is 62208, while the sum is 40.

The square root of 668839 is about 817.8257760673. The cubic root of 668839 is about 87.4528289966.

The spelling of 668839 in words is "six hundred sixty-eight thousand, eight hundred thirty-nine".