2. Let set $P=\{$ natural numbers not less than 3 $\}$, and define a function on set $P$ as follows: if $n \in P$, then $f(n)$ represents the smallest natural number that is not a divisor of $n$. Given that the range of $f(n)$ is set $M$, the relationship between the numbers $19, 88$ and $M$ is $\qquad$ .
$19 \in M, 88 \notin M$