a=2*3*m, b=3*5*m (m is a natural number and m≠0), if the greatest common factor of a and b is 21, what is the least common multiple of a and b.
a=2*3*m，b=3*5*m(m是自然数且m≠0)，如果a和b的最大公因数是21，则a和b的最小公倍数是多少．
<gadget id="calculator">3 * 7 * 2 * 5</gadget>
<output>210</output>

<result>210</result>