1) Weeks at #1
Adele's 21 has now spent 17 weeks at #1 on the Billboard 200, the most weeks at #1 since since The Bodyguard Soundtrack topped the chart for 20 weeks in late 1992/early 1993. That puts her in the company of only 26 other albums that have topped the albums chart for that long, the champion being the South Pacific cast album from 1949, which was the nation's most popular album for 69 weeks. See the full list here.
2) Number One Singles
With "Set Fire to the Rain" having ascent to the top of the Hot 100, 21 now has three #1 hits under its belt. That puts the album in the rather exclusive camp of albums to have had three or more #1 hits.
With Katy Perry's Teenage Dream scoring five #1 hits recently, there was much written (including by me) about how there are nine albums with four or more #1s (including two with five).
The club of albums with at least three #1s widens the circle a bit, but is still a pretty exclusive group of just 19 albums:
The Supremes - Where Did Our Love Go (1964): Where Did Our Love Go, Baby Love, Come See About Me
The Beatles - Help! (1965): Ticket to Ride, Help!, Yesterday
The Beatles - Magical Mystery Tour (1967): Penny Lane, All You Need is Love, Hello Goodbye
The Beatles - Let It Be (1970): Get Back, Let It Be, The Long and Winding Road
Bee Gees - Spirits Having Flown (1979): Too Much Heaven, Tragedy, Love You Inside Out
Wham! - Make It Big (1984): Wake Me Up Before You Go-Go, Careless Whisper, Everything She Wants
Whitney Houston (1985): Saving All My Love for You, How Will I Know, The Greatest Love of All
Madonna - True Blue (1986): Live to Tell, Papa Don't Preach, Open Your Heart
Milli Vanilli - Girl You Know It's True (1989): Baby Don't Forget My Number, Girl I'm Gonna Miss You, Blame It On the Rain
Wilson Phillips (1990): Hold On, Release Me, You're in Love
Mariah Carey - Daydream (1995): Fantasy, One Sweet Day, Always Be My Baby (*Notable for having three #1 hits and no other official singles)
Monica - The Boy Is Mine (1998): The Boy Is Mine, The First Night, Angel of Mine
Christina Aguilera (1999): Genie in a Bottle, What a Girl Wants, Come On Over Baby (All I Want Is You)
Justin Timberlake - FutureSex/LoveSounds (2006): Sexyback, My Love, What Goes Around...Comes Around
Fergie - The Dutchess (2006): London Bridge, Glamorous, Big Girls Don't Cry
Rihanna - Good Girl Gone Bad/Good Girl Gone Bad (Reloaded)(2007/2008): Umbrella, Take a Bow, Disturbia
The Black Eyed Peas - The E.N.D (2009): Boom Boom Pow, I Gotta Feeling, Imma Be
Rihanna - Loud (2010): Only Girl, What's My Name, S&M
Adele - 21 (2011): Rolling in the Deep, Someone Like You, Set Fire to the Rain