What is the smallest natural number with 18 factors?
有18个因数的最小自然数是多少．
<gadget id="calculator">2 ** 2</gadget>
<output>4</output>

<gadget id="calculator">3 ** 2</gadget>
<output>9</output>

<gadget id="calculator">4 * 9 * 5</gadget>
<output>180</output>

<result>180</result>