They've wanted it that way for 33 years: Happy anniversary, Backstreet Boys

Backstreet Boys perform at Sphere Las Vegas (Rich Fury)

Backstreet Boys have had it goin' on for 33 years.

The group considers April 20 their anniversary because on that day in 1993, Brian Littrell flew from Kentucky to Orlando, Florida, to officially join the group, completing the lineup that already included his cousin Kevin Richardson, Nick Carter, Howie Dorough and AJ McLean.

And while the group has had its ups and downs over the years — Kevin left at one point, but they continued as a four-piece — they've never actually split up. That's why on Monday the group was able to post about their 33rd anniversary.

On Instagram, they shared a montage of their recent activities, including their T-Mobile Super Bowl ad and their residency at Sphere Las Vegas. "One for the books!" they wrote. "Happy Backstreet Boys Day everyone!! 33 years strong because of each of you. Here we go 34."

In May, Backstreet Boys will perform at the BottleRock Napa Valley festival in California, and in July they'll resume their Sphere residency, which runs through Aug. 29. They'll head to Dusseldorf, Germany, in September to do a residency there from Sept. 25 through Oct. 7.