Updated

Presidential-hopeful Donald Trump has sold his penthouse in New York's Trump Park Avenue building for $21 million, according to real estate listing agent Michelle Griffith.

The developer and television star was the first and only owner of the unit located on the 24th floor of the 32-story tower on Park Avenue at 59th Street, though he never resided there, Ms. Griffith said.

The 6,200-square-foot penthouse has 10-foot ceilings, five bedrooms, seven bathrooms and a powder room, the listing notes. The unit was priced at $35 million in 2013; it was last offered at $24.995 million, according to public records.

Ivanka Trump, executive vice president of development and acquisitions of the Trump Organization and Mr. Trump's daughter, confirmed the sale.

Ms. Griffith, an agent with Trump International Realty, said there was an offer to rent the floor-through apartment for more than $80,000 a month, before Mr. Trump completed the sale. "In his mind, it was a strong market and it was a good time to get a deal done," Ms. Griffith explained.

Mr. Trump bought the building in 2001 for $115 million, The Wall Street Journal reported at the time. He has since converted the former Delmonico Hotel into a luxury condo building.

The buyer's agents, Alatia Bradley Bach and Leighton Candler of Corcoran Group, declined to name their client. Ms. Griffith wouldn't disclose the buyer's identity, but said it was purchased by a couple residing in the U.S. who own other homes in the country.

Ms. Trump, who lives in the Park Avenue building, said the sale is unrelated to Mr. Trump's presidential campaign. "My father is in the business of real estate," she said, noting the sale wasn't related to political fundraising.

In a statement, Mr. Trump said the sale "is a testament to the building, its incredible location and the strength of the Trump Brand."

The Republican presidential candidate has assets worth at least $1.5 billion, ranging from stakes in real estate and entertainment companies to restaurants, according to a federal disclosure form. He has said he is worth more than $10 billion, but the form isn't designed to account for such wealth.