Find the largest square number with the following properties: after erasing its ones and tens digits, it is still a perfect square number (the erased two digits are not all 0).
求具有下列性质的最大的平方数：在抹去它的个位数字和十位数字后仍为完全平方数(被抹去的两位数不全为0)．
<gadget id="calculator">41 ** 2</gadget>
<output>1_681</output>

<result>1_681</result>