666805 has 8 divisors (see below), whose sum is σ = 842400. Its totient is φ = 505296.

The previous prime is 666773. The next prime is 666811. The reversal of 666805 is 508666.

666805 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 666805 - 2⁵ = 666773 is a prime.

It is an Ulam number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3415 + ... + 3604.

It is an arithmetic number, because the mean of its divisors is an integer number (105300).

2⁶⁶⁶⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

666805 is a deficient number, since it is larger than the sum of its proper divisors (175595).

666805 is a wasteful number, since it uses less digits than its factorization.

666805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7043.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 666805 is about 816.5812880540. The cubic root of 666805 is about 87.3640883206.

It can be divided in two parts, 666 and 805, that multiplied together give a triangular number (536130 = T₁₀₃₅).

The spelling of 666805 in words is "six hundred sixty-six thousand, eight hundred five".