a=2*3*m, b=3*3*m (m is a non-zero natural number), and the greatest common factor of a and b is 21, then what is the least common multiple of a and b.
a=2*3*m，b=3*3*m(m为非零自然数)，且a、b的最大公因数是21，那么a、b的最小公倍数是多少．
<gadget id="calculator">3 * 7 * 3 * 2</gadget>
<output>126</output>

<result>126</result>