It is a sphenic number, since it is the product of 3 distinct primes.
It is a 7-Lehmer number, since φ(99991111) divides (99991111-1)7.
It is a cyclic number.
It is a nialpdrome in base 10.
It is a zygodrome in base 10.
It is a congruent number.
It is an upside-down number.
Almost surely, 299991111 is an apocalyptic number.
99991111 is a wasteful number, since it uses less digits than its factorization.
99991111 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 90113.
The square root of 99991111 is about 9999.5555401228. Note that the first 4 decimals coincide. The cubic root of 99991111 is about 464.1451299260.
The spelling of 99991111 in words is "ninety-nine million, nine hundred ninety-one thousand, one hundred eleven".