9991900 has 36 divisors (see below), whose sum is σ = 21851032. Its totient is φ = 3965760.

The previous prime is 9991879. The next prime is 9991939. The reversal of 9991900 is 91999.

It is a super-2 number, since 2×9991900² = 199676131220000, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 9991900.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15994 + ... + 16606.

Almost surely, 2^9991900 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 9991900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (10925516).

9991900 is an abundant number, since it is smaller than the sum of its proper divisors (11859132).

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

9991900 is a wasteful number, since it uses less digits than its factorization.

9991900 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 790 (or 783 counting only the distinct ones).

The product of its (nonzero) digits is 6561, while the sum is 37.

The square root of 9991900 is about 3160.9966782646. The cubic root of 9991900 is about 215.3852835537.

The spelling of 9991900 in words is "nine million, nine hundred ninety-one thousand, nine hundred".