a, b, c are all natural numbers, the product of a and b is 221, the product of b and c is 187, and the product of c and a is 143. What is the sum of these three natural numbers?
a、b、c都是自然数，a与b的积是221，b与c的积是187，c与a的积是143．这三个自然数的和是多少．
<gadget id="calculator">13 + 17 + 11</gadget>
<output>41</output>

<result>41</result>