This is by far his biggest collar!

An NYPD cop had an extra buck in his pocket after buying tickets for the historic $1.6 billion Powerball drawing in January so he plunked it down for a Mega-Millions quick pick — and about 6 months later, he dispatched his wife to collect a giant check for about $65 million.

Vito Viola, a sergeant in the 120th precinct who has been on the force since 2005, was just following orders — from his wife — when he picked up the Powerball tickets.

But on on his drive back to their Westerleigh home, he realized he had a spare $1 so Viola swung by the Willowbrook Deli for an extra ticket, a quick pick Mega Millions with the numbers 11, 39, 51, 57, 75 and a Mega Ball 2.

The next morning, it proved to be the best buck he ever spent.

“I think I almost had a heart attack,” his wife, Nancy, said Thursday as she recalled the moment she figured out that they had won.

“I just couldn’t believe what I was seeing, so I asked my husband to come over to look. He just kept looking at the screen three or four times and he was in shock,” the 37-year-old housewife added.

They accepted a lump-sum payment of $64,796,160 after taxes and withholding — a few tax brackets up from Viola’s annual salary of $117,000.

Top cop Bill Bratton was happy to hear of one of the city’s Finest won big, saying “Lucky him!” at a separate press conference Thursday.

Bratton left it up to Viola to decide whether or not to stay on the force.

“If you hit the lottery at $65 million, you could be tempted to make some changes in your lifestyle,” he said. “We’ll leave that up to him.”

Up until Thursday, the Violas had kept their newfound fortune a secret, though he stopped reporting to work starting in February, according to law enforcement sources.

“I heard he got another job and I said, ‘I hope he’s making a lot of money after giving up his pension,'” a cop who knew Viola when he was a community affairs officer in the 68th precinct said.

He laughed when he found out Viola was the mystery lottery winner, joking, “I guess he did get a new job with a lot of money.”

Not even their neighbors or his fellow boys in blue knew.

“They never said a word. I just found out watching the news and I’m shaking,” one neighbor told The Post.

Viola and his wife are being careful with their stash of cash, creating a limited liability company, The Orbity Fund LLC, shortly after they claimed the ticket in March to manage their money.

“I’ve thought about my plans and I want to make some investments and just be secure for the future,” Nancy said.

Their win continues Staten Island’s lucky streak, as they are the third big winners from Richmond County since December including two residents who hit the $7-million jackpot on the Golden Ticket.

A total of 33 Staten Islanders have become millionaires thanks to lottery games since 2010.

And there will be another lucky shot for a New Yorker Friday, as the Mega Millions jackpot rose to $415 million — the third largest in the game’s history.

Additional reporting by Daniel Prendergast