666845 has 8 divisors (see below), whose sum is σ = 805464. Its totient is φ = 529984.

The previous prime is 666829. The next prime is 666857. The reversal of 666845 is 548666.

It can be written as a sum of positive squares in 4 ways, for example, as 470596 + 196249 = 686^2 + 443^2 .

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 666845 - 2⁴ = 666829 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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, 647 + ... + 1323.

It is an arithmetic number, because the mean of its divisors is an integer number (100683).

2⁶⁶⁶⁸⁴⁵ is an apocalyptic number.

It is an amenable number.

666845 is a deficient number, since it is larger than the sum of its proper divisors (138619).

666845 is a wasteful number, since it uses less digits than its factorization.

666845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 879.

The product of its digits is 34560, while the sum is 35.

The square root of 666845 is about 816.6057800432. The cubic root of 666845 is about 87.3658352050.

The spelling of 666845 in words is "six hundred sixty-six thousand, eight hundred forty-five".