9966321666 has 24 divisors (see below), whose sum is σ = 24678511104. Its totient is φ = 2847520440.

The previous prime is 9966321647. The next prime is 9966321671. The reversal of 9966321666 is 6661236699.

It is a happy number.

It is a nude number because it is divisible by every one of its digits.

It is a Curzon number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39548770 + ... + 39549021.

It is an arithmetic number, because the mean of its divisors is an integer number (1028271296).

Almost surely, 2^9966321666 is an apocalyptic number.

9966321666 is an abundant number, since it is smaller than the sum of its proper divisors (14712189438).

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

9966321666 is a wasteful number, since it uses less digits than its factorization.

9966321666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79097806 (or 79097803 counting only the distinct ones).

The product of its digits is 3779136, while the sum is 54.

The square root of 9966321666 is about 99831.4663119800. The cubic root of 9966321666 is about 2152.0133774326.

The spelling of 9966321666 in words is "nine billion, nine hundred sixty-six million, three hundred twenty-one thousand, six hundred sixty-six".