Adele's 'Hello' Aiming for Record U.S. Digital Sales Week
"You kind of want to shout it out, run around in the streets yelling to random strangers what you've just done," he added.
"Hello" was released Friday, and it topped the iTunes singles chart in 85 countries. The music video broke the Vevo record for most views in a day with 27.7 million.
"Hello" is Adele's first album single since releasing 2011's 21, her sophomore album that sold more than 11 million units in the United States and won the Grammy Award for album of the year, among other accolades.
"I'm still in shock, honestly. ... I was just pretty blown away," Kurstin said of the insta-success of "Hello."
Kurstin, who has worked with Pink, Lily Allen, Katy Perry and Taylor Swift, said he and Adele were supposed to work together on music for 21, but it didn't pan out. On 25, which Adele will release Nov. 20, he also contributed to the tracks "Water Under the Bridge" and "Million Years Ago."
Kurstin said he felt pressure before meeting with Adele since this was her follow-up to 21. But that changed once he set foot in the studio, and they started working on songs last year, including "Hello."
"She's just so wonderful to be around. She is funny and she's just so down-to-earth. ... You can immediately relate to her and connect with her," Kurstin said. "I really felt very comfortable around her because she makes you feel that way. She's just cool, and then she gets on the microphone and of course blows your mind."
Greg Kurstin: The 17-Year Overnight Success
Kurstin's writing and production credits include pop smashes like Sia's "Chandelier," Kelly Clarkson's "Stronger (What Doesn't Kill You)" and Ellie Goulding's "Burn." He is half the indie duo The Bird and the Bee, which released its fourth album this year.
Kurstin is also working with another Grammy album of the year winner: He produced Beck's new single, "Dreams," and is producing other tracks on the rock singer's follow-up to 2014's "Morning Phase," which won the top Grammy earlier this year.
"I used to play in his band, actually," said Kurstin, who added that it's the first time he's officially writing and producing for Beck.