66666 is nontrivially palindromic in base 10.
It is a nude number because it is divisible by every one of its digits.
66666 is a nontrivial repdigit in base 10.
It is a plaindrome in base 10.
It is a nialpdrome in base 10.
It is a zygodrome in base 10.
It is an unprimeable number.
66666 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
266666 is an apocalyptic number.
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
66666 is a wasteful number, since it uses less digits than its factorization.
66666 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 317.
The square root of 66666 is about 258.1975987495. The cubic root of 66666 is about 40.5478781433.
The spelling of 66666 in words is "sixty-six thousand, six hundred sixty-six".