2. If five pairwise coprime distinct integers $a_{1}, a_{2}, \cdots, a_{5}$ are chosen from $1,2, \cdots, n$, among them there is always one integer that is a prime number, find the maximum value of $n$.
Hint If $n \geqslant 49$, take the integers $1, 2^{2}, 3^{2}, 5^{2}, 7^{2}$. These five integers are five different integers that are pairwise coprime, but none of them is a prime number. Therefore, $n \leqslant 48$. Then prove it by contradiction.
The maximum value of $n$ is 48.