666905 has 8 divisors (see below), whose sum is σ = 810432. Its totient is φ = 526768.

The previous prime is 666901. The next prime is 666929. The reversal of 666905 is 509666.

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 666905 - 2² = 666901 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (666901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 389 + ... + 1218.

It is an arithmetic number, because the mean of its divisors is an integer number (101304).

2⁶⁶⁶⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

666905 is a deficient number, since it is larger than the sum of its proper divisors (143527).

666905 is a wasteful number, since it uses less digits than its factorization.

666905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1695.

The product of its (nonzero) digits is 9720, while the sum is 32.

The square root of 666905 is about 816.6425166497. The cubic root of 666905 is about 87.3684554005.

The spelling of 666905 in words is "six hundred sixty-six thousand, nine hundred five".