there's no longer a F21 category its only F1, F2, F2A, F2B, F3, F4. F1- unmarried sons and daughters (21 years of age and older) of U.S. citizens F2A - spouses and children (unmarried and under 21 years of age) of LPR F2B - unmarried sons and daughters (21 years of age and older) of LPR F3- married sons and daughters of U.S. citizens F4- brothers and sisters of U.S. citizens (if the U.S. citizen is 21 years of age and older)