(CNN)Lottery officials have this advice for the holder of the winning ticket from Tuesday night's $1.537 billion Mega Millions jackpot: Take a deep breath, then give us a call.
The winning numbers -- 5, 28, 62, 65 and 70, with a Mega Ball of 5 -- were sold at a KC Mart gas station and convenience store in upstate South Carolina outside Simpsonville, a city of about 18,000 near Greenville.
It's the largest US jackpot won by a single ticket, and it's the nation's second-largest jackpot ever, just short of a $1.586 billion Powerball prize split by three tickets in January 2016.
Now the big question is: Who won?
"Sign the back of that (ticket). Take a few days. Take that deep breath again. (Then) call the lottery," South Carolina Education Lottery Chief Operating Officer Tony Cooper said at a Wednesday news conference outside the store where the ticket was sold.
KC Mart, which sold the winning ticket, attracts visitors Wednesday near Simpsonville, South Carolina.
Store owner CJ Patel was "shaking right now, (with) goose bumps" while absorbing the news his establishment -- some five miles from the nearest interstate -- sold the winning ticket, he told CNN affiliate WYFF in Greenville shortly before the news briefing.
Patel's store gets $50,000 for selling the ticket, and he said he'll "do some good with that money."
As for the ticket holder?
"Whoever the winner is, hopefully spends that money locally and (does) some good stuff for the community," Patel said.
Winner could choose to withhold name
We might be waiting awhile to learn who won. The winner (or winners, if the buyer was part of a pool) has 180 days from the date of sale to claim the prize.
And South Carolina is one of several states to let lottery winners withhold their names from the public, so there's no guarantee the identity in this case will be released.
"Our board has a policy to protect the winner because of all the risks associated with having that much money," South Carolina Education Lottery Executive William Hogan Brown told ABC's "Good Morning America" on Wednesday.
Whoever it is, the ticket holder is set to claim a monstrous amount of cash. The winner can pick a one-time cash option, which would be a cool $878 million before taxes.
Otherwise, the full $1.537 billion jackpot -- again, minus taxes -- would be paid in annuities over 29 years.
Only one ticket matched all the numbers to win the jackpot, Mega Millions said. A whopping 36 tickets nationwide matched five of the six numbers for second-prize tickets.
Mega Millions officials had earlier estimated that Tuesday night's prize would reach $1.6 billion, but the total wasn't finalized until after sales stopped shortly before the drawing.
Still, the prize smashes the old Mega Millions record jackpot of $656 million, set in March 2012.
"This is truly a historic occasion. We're so happy for the winner, and we know the South Carolina Education Lottery can't wait to meet the lucky ticket holder," said Gordon Medenica, lead director of the Mega Millions Group.
Jackpot had been building since July
Mega Millions is played in 44 states as well as Washington, D.C., and the US Virgin Islands. A ticket costs $2 -- and the winner beat the odds of 1 in 302 million.
The jackpot has been rolling since July 24 when a California office pool of 11 co-workers shared a $543 million prize.
The next Mega Millions drawing is Friday, and the jackpot will reset itself to $40 million -- or $22.8 million cash.
But wait ... there's still the Powerball
Mega Millions aside, the Powerball drawing is Wednesday, and the jackpot for that is an estimated $620 million.
The Powerball has climbed since the last winning ticket in New York took home the jackpot in August, and it has had 20 drawings since then without a winner. Wednesday's will be the third-largest Powerball jackpot.
CORRECTION: An earlier version of this story incorrectly reported the Mega Millions jackpot was the world's largest. It has been corrected.
