991199019900 has 288 divisors, whose sum is σ = 3177511001280. Its totient is φ = 237478625280.

The previous prime is 991199019893. The next prime is 991199019919. The reversal of 991199019900 is 9910991199.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 9951546 + ... + 10050654.

It is an arithmetic number, because the mean of its divisors is an integer number (11033024310).

Almost surely, 2^991199019900 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 991199019900, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1588755500640).

991199019900 is an abundant number, since it is smaller than the sum of its proper divisors (2186311981380).

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

991199019900 is a wasteful number, since it uses less digits than its factorization.

991199019900 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99233 (or 99226 counting only the distinct ones).

The product of its (nonzero) digits is 531441, while the sum is 57.

The spelling of 991199019900 in words is "nine hundred ninety-one billion, one hundred ninety-nine million, nineteen thousand, nine hundred".