It’s a long, long way — spiritually if not physically — from Joshua Tree to Las Vegas.

But as U2 prepares to launch its first residency in Sin City on Friday night, the Irish icons dropped the new single “Atomic City” — and its video — earlier in the same day.

Hey, they didn’t become one of the biggest rock bands of all time without learning a thing or two about promotional synergy.

And as they prepare to go Vegas — where no respectable band would have dared to go back in the day when they ruled rock — “Atomic City” finds the quintessentially earnest quartet coming out swinging and swaggering rather than taking themselves so seriously.

“I’m ready for bright lights…I came here for the fight/I’m front row in Las Vegas/And there’s a big one on tonight,” sings Bono in a not-so-subtle nod to “U2: UV Achtung Baby Live At Sphere,” their Sept. 29- Dec. 16 residency that christens the $2.3 billion Sphere venue in the Venetian Resort.

Revisiting the dance-rock rhythms of U2’s “Zooropa”/”Pop” era, “Atomic City” — a ’50s nickname for Las Vegas — is a fun party song, complete with handclaps, for the ultimate party town.

Will it join the cannon of U2 classics? No. But, evoking the punchy punk-pop of, say, Green Day, it shows that they’ve still got the hooks — even if it’s been a minute since they’ve had anything resembling a hit. This sounds like it actually could be one — or at least that it deserves to be.

And to top it off, the “Atomic City” video — also released on Friday — finds U2 revisiting the same Sin City street where they filmed their “I Still Haven’t Found What I’m Looking For” clip over 36 years ago.

Viva Las Vegas indeed.