666859 has 4 divisors (see below), whose sum is σ = 706104. Its totient is φ = 627616.

The previous prime is 666857. The next prime is 666871. The reversal of 666859 is 958666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 666859 - 2¹ = 666857 is a prime.

It is a super-3 number, since 3×666859³ = 889658444196233337, which contains 333 as substring.

It is a Duffinian number.

666859 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (666857) 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 3 ways as a sum of consecutive naturals, for example, 19597 + ... + 19630.

It is an arithmetic number, because the mean of its divisors is an integer number (176526).

2⁶⁶⁶⁸⁵⁹ is an apocalyptic number.

666859 is a deficient number, since it is larger than the sum of its proper divisors (39245).

666859 is a wasteful number, since it uses less digits than its factorization.

666859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39244.

The product of its digits is 77760, while the sum is 40.

The square root of 666859 is about 816.6143520659. The cubic root of 666859 is about 87.3664465980.

The spelling of 666859 in words is "six hundred sixty-six thousand, eight hundred fifty-nine".