9991220800 has 168 divisors, whose sum is σ = 27328197312. Its totient is φ = 3564288000.

The previous prime is 9991220797. The next prime is 9991220801. The reversal of 9991220800 is 80221999.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is not an unprimeable number, because it can be changed into a prime (9991220801) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 927445 + ... + 938155.

Almost surely, 2^9991220800 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 9991220800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13664098656).

9991220800 is an abundant number, since it is smaller than the sum of its proper divisors (17336976512).

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

9991220800 is a wasteful number, since it uses less digits than its factorization.

9991220800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10797 (or 10782 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 9991220800 is about 99956.0943614745. The cubic root of 9991220800 is about 2153.8040316723.

The spelling of 9991220800 in words is "nine billion, nine hundred ninety-one million, two hundred twenty thousand, eight hundred".