9991808 has 32 divisors (see below), whose sum is σ = 20049120. Its totient is φ = 4960000.

The previous prime is 9991771. The next prime is 9991811. The reversal of 9991808 is 8081999.

It is a tau number, because it is divible by the number of its divisors (32).

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, 31973 + ... + 32283.

It is an arithmetic number, because the mean of its divisors is an integer number (626535).

Almost surely, 2^9991808 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 9991808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10024560).

9991808 is an abundant number, since it is smaller than the sum of its proper divisors (10057312).

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

9991808 is a wasteful number, since it uses less digits than its factorization.

9991808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 576 (or 564 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 44.

The square root of 9991808 is about 3160.9821258590. The cubic root of 9991808 is about 215.3846225013.

The spelling of 9991808 in words is "nine million, nine hundred ninety-one thousand, eight hundred eight".