The seven-times platinum LP, which was today named as the most downloaded album of all time on Amazon.co.uk, has now spent the most consecutive weeks in pole position for a solo artist's studio album.
Adele's effort previously became the fastest album to sell one million copies between January and March, and broke the record for most downloads in the UK.
The London singer also dethroned Madonna as the female artist to have spent the longest time at number one on the album chart.
Sandwiched between 21 and Adele's previous album 19 is Katy B and her debut LP On A Mission, while Jessie J completes the Brit School reunion after climbing four places to five with Who You Are.
Also shuffling upwards this week are Michael Buble's Crazy Love, which advances five spots to seven in its 77th week of release, former number one Doo Wops & Hooligans by Bruno Mars, up three to eight, and Elbow's Build A Rocket Boys!, which is at nine from last Sunday's 14.
The top ten is rounded out by a new entry from Scottish indie rockers Glasvegas entitled Euphoric/Heartbreak, while Mother's Day favourites Ronan Keating, Mary Byrne and Eva Cassidy all tumble into the double digits in the aftermath of the special day.
Keating's Burt Bacharach collaboration When Ronan Met Burt slips from three to 11, Byrne's Mine & Yours is down nine to 15 in its second week of release, while Cassidy collection Simply Eva goes from 10 to 19.
Just beyond the upper half of the chart, Katy Perry's Teenage Dream is buoyed from 31 to 22 following the release of her long-awaited E.T. video, but Chase & Status win the title of biggest climber this week with No More Idols, which is up 15 places to 24.
The top ten in full:
1. (1) Adele: '21'
2. (-) Katy B: 'On A Mission'
3. (2) Adele: '19'
4. (5) Rihanna: 'Loud'
5. (9) Jessie J: 'Who You Are'
6. (4) The Overtones: 'Good Ol' Fashioned Love'
7. (12) Michael Bublé: 'Crazy Love'
8. (11) Bruno Mars: 'Doo Wops & Hooligans'
9. (14) Elbow: 'Build A Rocket Boys!'
10. (-) Glasvegas: 'Euphoric/Heartbreak'
Source: Official Charts Company
> Click here for this week's singles chart
Watch 'Rolling In The Deep' from Adele's number one album 21 below: