999966 has 32 divisors (see below), whose sum is σ = 2217600. Its totient is φ = 298080.

The previous prime is 999961. The next prime is 999979. The reversal of 999966 is 669999.

999966 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999961) by changing a digit.

999966 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 15 ways as a sum of consecutive naturals, for example, 7125 + ... + 7263.

It is an arithmetic number, because the mean of its divisors is an integer number (69300).

2⁹⁹⁹⁹⁶⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 999966, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1108800).

999966 is an abundant number, since it is smaller than the sum of its proper divisors (1217634).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

999966 is a wasteful number, since it uses less digits than its factorization.

999966 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 264.

The product of its digits is 236196, while the sum is 48.

The square root of 999966 is about 999.9829998555. The cubic root of 999966 is about 99.9988666538.

The spelling of 999966 in words is "nine hundred ninety-nine thousand, nine hundred sixty-six".