Adding to 999999000000 its reverse (999999), we get a palindrome (999999999999).
Subtracting from 999999000000 its reverse (999999), we obtain a square (999998000001 = 9999992).
999999000000 divided by its reverse (999999) gives a 6-th power (1000000 = 106).
It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.
It is a nialpdrome in base 10.
It is a zygodrome in base 10.
It is a congruent number.
Almost surely, 2999999000000 is an apocalyptic number.
999999000000 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 999999000000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2533617569280).
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
999999000000 is a wasteful number, since it uses less digits than its factorization.
999999000000 is an odious number, because the sum of its binary digits is odd.
The spelling of 999999000000 in words is "nine hundred ninety-nine billion, nine hundred ninety-nine million", and thus it is an aban number.