After 546 days — and more than 9.7 million albums sold — Adele's unstoppable 21 will do the unthinkable on next week's Billboard albums chart: drop outside the Top 10.

Yes, according to Nielsen SoundScan, 21 will fall to #12 next week, marking its lowest chart position since debuting at #1 in early March 2011 (its previous low was #9 back in July). It brings to a close a record-setting run for the album, which had already logged more weeks in the Top 10 than any other album by a female artist, and had racked up an astonishing 24 weeks at #1, the sixth-most in the chart's history.

On the one-year anniversary of its debut on the chart, we commemorated 21's achievements (at the time, it had spent 40 percent of the year at #1, and had sold more copies than Katy Perry's Teenage Dream, Lady Gaga's Born This Way, Rihanna's Talk That Talk and Beyoncé's <4> ... combined), so, now that it's finally fallen into the chart's double digits, we figured we should also take a look back at some of the highlights from its 78-week run in the Top 10, by the numbers.

2: Number of albums that have spent a longer time in the Top 10 than 21, according to SoundScan. Those albums? Bruce Springsteen's Born in the U.S.A. (84 weeks) and "The Sound of Music" soundtrack (109 weeks).

20: Number of consecutive weeks 21 sold more than 100,000 copies, from September 4, 2011 to January 15, 2012. It dipped to (only) 95,000 copies the following week, then reeled off a stretch of an additional 11 weeks of six-digit sales, highlighted by a record-setting post-Grammy haul of nearly 730,000 albums sold.

45: Number of other albums that have held the #1 spot on the Billboard chart during 21's run in the Top 10.

68: Weeks after its release that 21 managed to grab the #1 spot on the chart, the 24th time it accomplished the feat. Over the course of its 78 weeks in the Top 10, 21 has also had runs of five and 10 consecutive weeks at #1.

24,002: Number of copies 21 sold this week, its lowest figure since being released. Of course, that number is only 20,000 less than Cake's Showroom of Compassion, which holds the record for lowest-selling record to open at #1 in the Nielsen SoundScan era.

3,900,000: Number of copies 21 has sold in 2012, to date.

5,800,000: Number of copies 21 sold in 2011.

430,000,000: Total number of all albums sold in 2011 and 2012 ... 23 percent of which have been copies of 21.