9966321664 has 72 divisors (see below), whose sum is σ = 21469511700. Its totient is φ = 4599054336.

The previous prime is 9966321647. The next prime is 9966321671. The reversal of 9966321664 is 4661236699.

It can be written as a sum of positive squares in 2 ways, for example, as 9216000000 + 750321664 = 96000^2 + 27392^2 .

It is a Harshad number since it is a multiple of its sum of digits (52).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1701012 + ... + 1706860.

Almost surely, 2^9966321664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9966321664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10734755850).

9966321664 is an abundant number, since it is smaller than the sum of its proper divisors (11503190036).

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

9966321664 is an frugal number, since it uses more digits than its factorization.

9966321664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5896 (or 5864 counting only the distinct ones).

The product of its digits is 2519424, while the sum is 52.

The square root of 9966321664 is about 99831.4663019631. The cubic root of 9966321664 is about 2152.0133772886.

The spelling of 9966321664 in words is "nine billion, nine hundred sixty-six million, three hundred twenty-one thousand, six hundred sixty-four".