9991800 has 288 divisors, whose sum is σ = 41976480. Its totient is φ = 2073600.

The previous prime is 9991771. The next prime is 9991811. The reversal of 9991800 is 81999.

9991800 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

9991800 is an esthetic number in base 16, because in such base its adjacent digits differ by 1.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 163770 + ... + 163830.

Almost surely, 2^9991800 is an apocalyptic number.

9991800 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9991800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (20988240).

9991800 is an abundant number, since it is smaller than the sum of its proper divisors (31984680).

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

9991800 is a wasteful number, since it uses less digits than its factorization.

9991800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103 (or 91 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 36.

The square root of 9991800 is about 3160.9808604292. The cubic root of 9991800 is about 215.3845650183.

The spelling of 9991800 in words is "nine million, nine hundred ninety-one thousand, eight hundred".