And she's telling the world about it via a gold 18-wheeler. 

Katy's new album will be called 'Prism' and is coming out on October 22.

'Prism' will be the follow-up to Katy's multi-platinum international smash 'Teenage Dream', released three years ago next month.

Katy tweeted Monday, "Find the #PRISM semi, take a picture and I'll RT you. Don't worry, Los Angeles is just the first stop on the map."

It didn't take fans any time at all to figure out that pretty big clue -- or to spot the hard-to-miss rolling billboard -- and begin posting photos of the semi as it drove around Los Angeles with the words "KATY PERRY -- PRISM -- 10-22-13" emblazoned on the trailer in 6-foot-tall letters.

Adam Lambert, twitter