999666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a nude number because it is divisible by every one of its digits.
999666 is a strobogrammatic number because it is the same when read upside-down.
It is a nialpdrome in base 10.
It is a zygodrome in base 10.
2999666 is an apocalyptic number.
It is a practical number, because each smaller number is the sum of distinct divisors of 999666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1185600).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
999666 is a wasteful number, since it uses less digits than its factorization.
999666 is an evil number, because the sum of its binary digits is even.
The square root of 999666 is about 999.8329860532. The cubic root of 999666 is about 99.9888654269.
The spelling of 999666 in words is "nine hundred ninety-nine thousand, six hundred sixty-six".