9866 is an esthetic number in base 8, because in such base its adjacent digits differ by 1.
It is a semiprime because it is the product of two primes.
It is a plaindrome in base 16.
It is a nialpdrome in base 10.
It is an unprimeable number.
29866 is an apocalyptic number.
9866 is a wasteful number, since it uses less digits than its factorization.
9866 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 4935.
The square root of 9866 is about 99.3277403347. The cubic root of 9866 is about 21.4476824218.
The spelling of 9866 in words is "nine thousand, eight hundred sixty-six".