666939 has 24 divisors (see below), whose sum is σ = 1117200. Its totient is φ = 350784.

The previous prime is 666937. The next prime is 666959. The reversal of 666939 is 939666.

It is not a de Polignac number, because 666939 - 2¹ = 666937 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a junction number, because it is equal to n+sod(n) for n = 666897 and 666906.

It is not an unprimeable number, because it can be changed into a prime (666937) 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 23 ways as a sum of consecutive naturals, for example, 1737 + ... + 2085.

It is an arithmetic number, because the mean of its divisors is an integer number (46550).

2⁶⁶⁶⁹³⁹ is an apocalyptic number.

666939 is a deficient number, since it is larger than the sum of its proper divisors (450261).

666939 is a wasteful number, since it uses less digits than its factorization.

666939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 379 (or 372 counting only the distinct ones).

The product of its digits is 52488, while the sum is 39.

The square root of 666939 is about 816.6633333265. The cubic root of 666939 is about 87.3699401083.

The spelling of 666939 in words is "six hundred sixty-six thousand, nine hundred thirty-nine".