9999664 has 40 divisors (see below), whose sum is σ = 20936160. Its totient is φ = 4612608.

The previous prime is 9999659. The next prime is 9999667. The reversal of 9999664 is 4669999.

It is a super-2 number, since 2×9999664² = 199986560225792, which contains 22 as substring.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9999667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10204 + ... + 11140.

It is an arithmetic number, because the mean of its divisors is an integer number (523404).

Almost surely, 2^9999664 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 9999664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10468080).

9999664 is an abundant number, since it is smaller than the sum of its proper divisors (10936496).

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

9999664 is a wasteful number, since it uses less digits than its factorization.

9999664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 997 (or 991 counting only the distinct ones).

The product of its digits is 944784, while the sum is 52.

The square root of 9999664 is about 3162.2245334574. The cubic root of 9999664 is about 215.4410560093.

The spelling of 9999664 in words is "nine million, nine hundred ninety-nine thousand, six hundred sixty-four".