Andy's View
"21 and Invincible" really applies to me, so I feel that it's about how perfect Andrew's life should be once he turns 21 and how he'll probably screw it up. He wants to get a big house, pay off his ex's, complain about taxes, and he even wants to get married but his Mom thinks he's too young so he'll go have fun instead.
Katie's View
I think this is one of Andrew's more personal songs. He seems to be always looking forward to turning 21, the ideal age in which he thinks "no one makes fun of me cuz I can't stand up for myself" because he is fianlly an adult. He also seems to be saying that he can't wait to "screw this up" cuz he finally has the power to do more. The song ends on "I'm in power for the hour, I guess today's gonna blow us away" meaning that since he is finally old enough to make an impact in the world, he is ready to blow the world away. Wow!