The length and width of a rectangle are both prime units, and the perimeter is 36 units. What is the maximum number of units in the area?
一个长方形的长和宽都是质数个单位，周长是36个单位，面积最多是多少个单位？
<gadget id="calculator">7 * 11</gadget>
<output>77</output>

<result>77</result>