It is known that the difference between two positive integers is 21, and the sum of their greatest common divisor and least common multiple is 287. What is the sum of these two numbers?
已知两个正整数的差是21，它们的最大公约数和最小公倍数的和是287，求这两个数的和是多少？
<gadget id="calculator">56 + 35</gadget>
<output>91</output>

<result>91</result>