WASHINGTON (AP) _ He's sometimes called the second most powerful man in America, but most Americans know next to nothing about Alan Greenspan _ the man who holds such sway over what a car or home loan will cost them.

He's supposed to be obscure. The chairman of the Federal Reserve works in secrecy, steering the nation's monetary policy. A stray word from him can send jittery markets fluttering up or down.

Greenspan has been loyal to the taciturn tradition. But with the Fed pushing up short-term interest rates for the seventh time in a year _ which means consumers will pay more to borrow money _ Greenspan's name is increasingly in the news.

Who is this guy?

Greenspan, 68, is reserved, almost shy, yet at ease in the Georgetown social whirl. He's a lover of numbers and dry statistics but toured with a swing band in his youth. He's a bespectacled, nerdy economist who dates NBC newswoman Andrea Mitchell and, before her, squired Barbara Walters to parties.

He is a conservative Republican, tutored by Ayn Rand in the glory of capitalism, and he dislikes government regulation almost as much as he hates inflation. Yet Greenspan has warmed up to the much more liberal President Clinton, raising eyebrows when he sat next to the first lady during Clinton's first State of the Union address.

Greenspan has said he is dedicated to guarding the Fed's independence but, like his predecessors, he has served as a behind-the-scenes adviser to the White House on economic policy. And recently he has become more visible _ speaking out in support of the administration's bailout of Mexico, and suggesting to Congress that it could curb entitlement spending by revising the Consumer Price Index.

If he seems a man of contradictions, it may be because he so seldom explains himself.

``It's incumbent on the chairman of the Federal Reserve to be circumspect in his remarks, because of the way the financial community interprets even the nuances of what he says,'' said William Niskanen, economist at the conservative Cato Institute and a former acting chairman of President Reagan's Council of Economic Advisers.

``Their pattern is to convey moods but not very much detail or specific information,'' Niskanen said. ``It's kind of a game they play.''

Greenspan has been known to joke that he learned to mumble after Reagan nominated him to the Fed post in 1987. He sometimes tells visitors, ``If I seem unduly clear to you, you must have misunderstood what I said.''

Although plainly more comfortable with conservatives, Greenspan's ease with Clinton may stem from their shared love of economic minutiae.

``He's the ultimate numbers cruncher,'' said David M. Jones, economist and author of a book on the Fed, ``The Buck Starts Here,'' which takes its title from a plaque on Greenspan's desk.

``I'll walk into his office, and he won't say `David, good morning' or `How are you.' He'll say, `David, do you have any numbers on inventories of imported goods' or something like that,'' Jones said.

Economists and journalists often rank the chairman of the Federal Reserve as second only to the president in power (although these days some might put House Speaker Newt Gingrich in there somewhere). ``He really relishes this role,'' Jones said.

Greenspan's father was a stock broker. His parents were divorced when he was a child, however, and it was his mother who raised him in Manhattan. He showed an early talent for math and an impressive recall of major league batting averages. Now he follows the Mets.

Greenspan studied music at the Juilliard School before dropping out for a year on the road as a saxophone and clarinet player. After a year he returned to school and studied economics at New York University, eventually earning his doctorate and becoming an economic consultant.

He met social philosopher Ayn Rand in 1952, and they became close friends. Greenspan has credited Rand with teaching him that capitalism ``is not only efficient and practical, but also moral.''