199 (one hundred [and] ninety-nine) is the natural number following 198 and preceding 200.
199 is a centered triangular number.[1]
It is a prime number and the fourth part of a prime quadruplet: 191, 193, 197, 199.[2]
199 is the smallest natural number that takes more than two iterations to compute its digital root as a repeated digit sum: 199 ↦ ↦ --> 1 + 9 + 9 = 19 ↦ ↦ --> 1 + 9 = 10 ↦ ↦ --> 1 + 0 = 1. {\displaystyle {\begin{aligned}199&\mapsto 1+9+9=19\\&\mapsto 1+9=10\\&\mapsto 1+0=1.\end{aligned}}} Thus, its additive persistence is three, and it is the smallest number of persistence three.[3]
