9991111212 has 84 divisors (see below), whose sum is σ = 26659450440.
Its totient is φ = 3273867072.
The previous prime is 9991111187. The next prime is 9991111223. The reversal of 9991111212 is 2121111999.
It is a Harshad number since it is a multiple of its sum of digits (36).
It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.
It is an unprimeable number.
It is a polite number, since it can be written in 27 ways as a sum of consecutive naturals, for example, 143008 + ... + 201080.
It is an arithmetic number, because the mean of its divisors is an integer number (317374410).
Almost surely, 29991111212 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 9991111212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13329725220).
9991111212 is an abundant number, since it is smaller than the sum of its proper divisors (16668339228).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
9991111212 is a wasteful number, since it uses less digits than its factorization.
9991111212 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 58154 (or 58137 counting only the distinct ones).
The product of its digits is 2916, while the sum is 36.
The square root of 9991111212 is about 99955.5461792891.
The cubic root of 9991111212 is about 2153.7961570277.
The spelling of 9991111212 in words is "nine billion, nine hundred ninety-one million, one hundred eleven thousand, two hundred twelve".