President Reagan is to meet with former president Carter Tuesday at the White House and deliver his first speech as president on international affairs Thursday, White House spokesmen said yesterday.

Reagan and Carter will spend 30 minutes together Tuesday afternoon in their first private meeting since Reagan has been in the White House.

The two men met briefly Thursday night with former presidents Ford and Nixon.

Carter will have just returned from the Cairo funeral of Egyptian President Anwar Sadat, and will be visiting Washington, staying at a townhouse on Lafayette Park that is the official residence for former presidents.

Reagan's speech on international economic affairs will be delivered at a luncheon of the World Affairs Council in Philadelphia. Reagan will be speaking a week before the 22-nation summit on international economic affairs in Cancun, Mexico.

In a recent speech to the annual meeting of the World Bank and International Monetary Fund here, Reagan stressed the importance of private investment and private development in the world's poorer nations.

Reagan is to follow his speech by attending two fund-raising events in New Jersey for Republican gubernatorial candidate Thomas Kean.

The president left yesterday afternoon for Camp David. Asked whether he would watch Sadat's funeral on television today, he said: "If they replay it at a later hour. I've heard it will be at 5:30 in the morning."