Mr. Trump took the unusual step of speaking publicly about his friend’s illness.

“I had a friend who went to a hospital the other day,” the president said from the White House. “He’s a little older, and he’s heavy, but he’s a tough person.”

Alluding to the lethal nature of the coronavirus, Mr. Trump added, “The speed and the viciousness, especially if it gets the right person, it’s horrible.”

The severity of Mr. Chera’s case was said to have helped persuade Mr. Trump to take the pandemic more seriously and to extend social distancing guidelines until the end of April.

“Boy, did that hit home,” Bill White, a prominent New York donor to Mr. Trump’s campaign, told Vanity Fair this month. “Stan is like one of his best friends.”

Stanley Isaac Chera was born on Oct. 22, 1942, in Brooklyn. He and his father, Isaac, founded and ran a chain of children’s specialty stores in the New York area.

Shortly after opening their first stores, they began acquiring the buildings they operated out of, then the buildings nearby, then entire blocks. Within a generation they had parlayed their holdings into one of New York’s biggest retail empires. Along the way, Stanley’s three sons — Richard, Haim and Isaac — became part of the business. Their real estate deals sometimes have run in the billions of dollars.

In addition to his wife and sons, Mr. Chera’s survivors include several grandchildren.

Despite having founded his empire on retail, Mr. Chera told The New York Times in 2010 that he hated to shop; he said he could buy 10 suits in 15 minutes.