Divide 13 into the sum of several natural numbers, and then calculate the product of these natural numbers, what is the maximum product obtained?
把13分成几个自然数的和，再求这几个自然数的乘积，所得到的乘积最大是多少．
<gadget id="calculator">3 * 3 * 3 * 4</gadget>
<output>108</output>

<result>108</result>