805666 has 8 divisors (see below), whose sum is σ = 1220544. Its totient is φ = 398820.

The previous prime is 805639. The next prime is 805687. The reversal of 805666 is 666508.

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

It is an unprimeable number.

805666 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1750 + ... + 2161.

It is an arithmetic number, because the mean of its divisors is an integer number (152568).

2⁸⁰⁵⁶⁶⁶ is an apocalyptic number.

805666 is a deficient number, since it is larger than the sum of its proper divisors (414878).

805666 is a wasteful number, since it uses less digits than its factorization.

805666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4016.

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

The square root of 805666 is about 897.5889928024. The cubic root of 805666 is about 93.0504216502.

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

The spelling of 805666 in words is "eight hundred five thousand, six hundred sixty-six".