Even British singer Adele was surprised by the 10th anniversary of her record-smashing "21" album on Sunday, posting an Instagram post featuring the famed album cover.

"21" came out January 24, 2011, in Europe before its North American release on Feb. 22 of that year.

"Well I never! Happy 10 years old friend!" Adele, 32, wrote in the Instagram caption. "It’s crazy how little I remember of what it was like and how I felt a decade ago. But Thank You from the bottom of my heart for letting us into your lives and letting me be a soundtrack to some of it."

Breakthrough debut album "19" brought Adele her first No. 1 record in 2008, with hits like "Making You Feel My Love," "Chasing Pavements" and "Hometown Glory."

But the singer's sophomore album "21," now the best selling album of the 21st century, propelled Adele to true superstar heights with hit singles "Rolling in the Deep,” the plaintive love song "Someone Like You" and "Set Fire to the Rain."

The album entered Billboard at No. 1 and topped the chart for 24 non-consecutive weeks, a SoundScan record. It spent more than 80 weeks in the top 10.

"21" brought Adele six trophies at the 54th annual Grammy Awards, including album, record and song of the year. The singer now has 15 Grammys.

It's been more than five years since Adele’s last album, "25."