Among the 5 natural numbers, the median is 4 and the mode is only 6. What is the largest sum of these 5 numbers?
5个自然数中，中位数是4，众数只有6，那么这5个数的和最大是多少
<gadget id="calculator">2 + 3 + 4 + 6 + 6</gadget>
<output>21</output>

<result>21</result>