2. If $a, b, c, d$ are four distinct positive integers, and satisfy $a b c d=2277$, then the maximum value of $a+b+c+d$ is $\qquad$
2. 84 .

Assume $a<b<c<d$. Note that,
$$
\begin{array}{l}
a b c d=2277=9 \times 253 \\
=3 \times 3 \times 11 \times 23 .
\end{array}
$$

Also, $3, 11, 23$ are all prime numbers, so the possible sets of $(a, b, c, d)$ that meet the conditions are:
$$
(1,9,11,23),(1,3,11,69),(1,3,23,33) \text {. }
$$

Therefore, the maximum value of $a+b+c+d$ is
$$
1+3+11+69=84 \text {. }
$$