The New York Times Co. has announced the reorganization of Times Books, the most prominent imprint in its book-publishing division. The move involves cutting the number of titles a year from 75 to 35, and reassigning 38 current projects to Harper & Row.

The announcement came as a surprise yesterday to several literary agents who received a mailgram from Times Books' interim president, William t. kerr.

The mailgram read in part, "The company remains strongly committed to trade book publishing. Greater emphasis will be placed on Times-related books, and the total number of titles to be published each season will be reduced. Harper & Row publishers Inc., the distinguished publishing company which has long sold and distributed Times Books, has told us it wants to publish under its own imprint the following titles for which you are the agent . . . accordingly, we have assigned the contracts and titles to Harper & Row, and you and your authors will hear within a few days from Edward Burlingame, publisher of Harper & Row . . . ."

The same mail brought the promised letters from Burlingame, announcing specific editorial assignments. Among the projects transferred are several nonfiction works on scientific subjects by Isaac Asimov, "The Americans" by a group of writers from the Economist magazine, the Burpee Vegetable Garden Cookbook and Benita Eisler's "Class Act" a non-fiction book about the class system in the United States.

"I think it is important to note that this was not a process of dumping crummy titles on Harper & Row," Kerr said yesterday. He added that Times Books still plans to publish the remainder of titles currently under contract, including a Craig Claiborne-Pierre Franey cookbook; Mimi Sheraton's "dining-out" book; two books on language by William Safire; works by Jack Anderson on oil; Joseph Goulden on the Korean War; and Peter Drucker's "Corporation In Crisis" scheduled for the spring of 1982.

Kerr stressed that the reorganization of Times Books is a natural step in the recent reorganization of the Times company itself, in which each division in its turn has come under scrutiny: "Times Books, in its actual profit and publishing performance, was at a break-even point in 1980, which I find an unsatisfactory performance.

"We think that by concentrating on fewer but stronger titles and building upon the resources of The New York Times," Kerr said, "we can create a high-quality and reasonably profitable trade book publishing house. Part of our energies will be devoted to tackling the development of books from the pages of the newspaper in areas not previously tapped."