1. If every prime factor of 2013 is a term in a certain arithmetic sequence $\left\{a_{n}\right\}$ of positive integers, then the maximum value of $a_{2013}$ is $\qquad$
$-, 1.4027$.
Notice that, $2013=3 \times 11 \times 61$.
If $3, 11, 61$ are all terms in a certain arithmetic sequence of positive integers, then the common difference $d$ should be a common divisor of $11-3=8$ and $61-3=58$. To maximize $a_{2013}$, the first term $a_{1}$ and the common difference $d$ should both be as large as possible. Thus, $a_{1}=3, d=2$.
Therefore, the maximum value of $a_{2013}$ is $3+2012 d=4027$.