If the product of two six-digit numbers \overline{124A72}, \overline{3184B7} is divisible by 99, what is the smallest two-digit number \overline{AB}?
如果两个六位数\overline{124A72}、\overline{3184B7}的乘积能够被99整除，那么两位数\overline{AB}最小是多少？
<result>21</result>