18. There is a positive integer, which is neither a prime number nor a perfect square, and has no prime factors less than 50. Then the smallest such positive integer is ( ).
(A) 3127
(B) 3133
(C) 3137
(D) 3139
(E) 3149
$\begin{array}{l}\text { 18. A. } \\ 53 \times 59=3127\end{array}$