666839 has 8 divisors (see below), whose sum is σ = 706560. Its totient is φ = 628056.

The previous prime is 666829. The next prime is 666857. The reversal of 666839 is 938666.

666839 = 50² + 51² + ... + 128².

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 666839 - 2⁴ = 666823 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666829) 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 7 ways as a sum of consecutive naturals, for example, 1634 + ... + 2000.

It is an arithmetic number, because the mean of its divisors is an integer number (88320).

2⁶⁶⁶⁸³⁹ is an apocalyptic number.

666839 is a deficient number, since it is larger than the sum of its proper divisors (39721).

666839 is a wasteful number, since it uses less digits than its factorization.

666839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 469.

The product of its digits is 46656, while the sum is 38.

The square root of 666839 is about 816.6021062917. The cubic root of 666839 is about 87.3655731768.

The spelling of 666839 in words is "six hundred sixty-six thousand, eight hundred thirty-nine".