Happy Birthday, Nick Jonas! Celebrate Youngest Jonas Brother's 21st Birthday with 5 Best Songwriting Efforts [VIDEOS]

The youngest Jonas Brother, Nick Jonas, is not a little boy anymore. Today (Sept. 16) marks the singer/songwriter's 21st birthday. Though Nick and his big brothers (Joe and Kevin) celebrated his milestone birthday by partying in Las Vegas, not all his fans could join him.

Since he's the main creative force behind the Jonas Brothers and has also found mild success on his own with The Administration, let's celebrate Nick's ability to legally drink by reliving his five best songwriting occasions.

5. "Lovebug"

From the Jonas Brothers' third studio album "A Little Bit Longer," "Lovebug" was co-written by Nick Jonas and his two brothers. The laidback, Jack Johnson-esque single showed the first signs of maturity from the growing boy band. The small guitars and soft vocals give the song an intimate vibe. The boppy guitar and singsong melody help to make it a total earworm, as well.

Of course, no Jonas Brothers best song would be complete without a lyrical analysis. And, "Lovebug" is a sweet little love song about finding someone after all felt lost. While it's not the most original song idea in the world, the relatability of lyrics have helped to make "Lovebug" a shining star in the Jonas discography and a fan favorite.

4. "Olive & An Arrow"

While the Jonas Brothers were on a musical hiatus in the early 2010s, Nick Jonas' side project The Administration released an album, "Who I Am." Full of more rock-inspired music than what the Jonas Brothers had done up to that point, "Who I Am" showed a maturity to Nick, even though he was only 17 years old when the album was released.

"Olive & An Arrow," an album track from the band's only studio album, is reminiscent of a harder John Mayer song, full of strong, strained vocals and a bluesy, hard-hitting melody, "Olive & An Arrow' is a different song for the Jonas catalog. The song also featured emotional lyrics (which is where Nick really shines) about a girl who is simultaneously peaceful and hurtful, hence the imagery in the song's title.

3. "First Time"

As Nick has gotten older, his songwriting abilities have only grown and grown. The second single from the Jonas Brothers' upcoming album "V," "First Time" shows variety in the types of songs Nick is capable of writing.

Full of atmospheric, hopeful melodies and winding vocals, "First Time" adds electronic elements smoothly into the signature pop-rock sound of the Jonas Brothers. It succeeds in sounding hopeful without being hokey and in creating layers upon layers of sound.

With other singles "Pom Poms" and "Neon" sounding markedly different from one another, it's clear that Nick Jonas (who also produced "V," in addition to writing the album's songs) has a diverse songwriting capability.

2. "Wedding Bells"

After hearing about ex-girlfriend Miley Cyrus' engagement to Liam Hemsworth, Jonas wrote the revelatory, honest "Wedding Bells." The track has since become a fan favorite, despite being unreleased and is frequently played live.

Though relatively upbeat in its tempo, "Wedding Bells" grooving beat is catchy, despite the song's heartbreaking lyrics. "No, I don't wanna love if it's not you / I don't wanna hear the wedding bells boom," Nick sings in the song's chorus. Other lyrics blatantly reference details about his relationship with Cyrus ("If you recall / Our anniversary falls on the 11th of June"). The honesty of this song makes it a true career highlight.

1. "What Do I Mean To You"

Speaking of revelatory songs from Nick Jonas, one song from "V" has huge buzz before the record even has an official release date. Blatantly naming ex Rita Ora in its second verse, "What Do I Mean To You" explores the anger following a particularly nasty break up.

The mad emotions of the song are highlighted by the strained screams from singers Joe and Nick during the chorus. "What Do I Mean To You" is far and away the hardest-hitting song from the Jonas Brothers, showing once again that Nick has the capabilities to write a wide variety of music. Though a studio version of the song has yet to be heard, it's already become one of the most highly anticipated songs from "V," and it's sure to usher in a new era for the Jonas Brothers.