SOME THINK of him as one of the greatest tunesmiths of all time. Others look upon him as president of a highly successful and still-growing record company. There are those who recognize him as one of the nation's most talented singers.

But if you are in Hollywood trying to look up Johnny Mercer, you're likely to find him hard at work doing nothing. Maybe he's leaning on the mailbox at Sunset and Vine, arguing with the paper boys about the Cards' miserable hitting. He's likely to be in a corner drug store, alone, scanning a mag and drinking root beer. Once in a while he goes out and shoots golf, or sneaks off to the beach to soak up the Sol, but he's been found, too, at midnight running over dozens of songs submitted by hopefuls in his office in the big new Capitol structure across from Radio City in Hollywood.

No one ever keeps close tabs on Mercer. He's elusive. He does things his own way and, incredibly, seems to get them done. When he was 17 he flew the coop, cutting out from his hometown, Savannah, to try New York as an actor. Not a single Broadway producer welcomed him. Somehow, the chance came for him to put lyrics to a melody that later was published as "Out of Breath." A comic by the name of Sterling Holloway performed it in a Theatre Guild presentation of "Garrick Gaieties," thus giving the young Georgian a start, but little else. So Johnny took a job on Wall Street.

"I found myself," he recalls, "punching holes in stock certificates. But I quit. My thumbs got sore."

No one would give him a chance to act and he was desperate. He recalled writing the song, so he tucked in his belt to its last notch and began turning out other ditties. Eventually he worked his way to an interview with Paul Whiteman, who was desperate for singers. Johnny had never done much singing, and had never worked with a band, but it was a way to eat and a way to get his own tunes performed. Whiteman liked both Johnny's singing and Johnny's songs.

"Here Come the British With a Bang,Bang" was one of Mercer's early efforts, in the early 1930's, which so intrigued Whiteman that he featured it on broadcasts and records until it was a hit. And it was through Pops Whiteman that Mercer met another young man who had flopped, as a lawyer, Hoagy Carmichael. Hoagy, from Indiana, and Mercer, from Georgia, promptly turned out "Lazybones." It was "Lazybones" that made Johnny. Now he was eating again.

Johnny went on the radio a few seasons later sharing the Camel cigarette show with Benny Goodman's band. At 26, Johnny was just about the youngest and most dynamic new personage in show business. Came Hollywood, and the frustrated actor found the motion picture producers eager to get his songs and just as eager to refuse him acting roles.

With men like Jerome Kern, Dick Whiting, Rube Bloom, Harold Arlen, Harry Warren, Vernon Duke, Matty Malneck and other top ASCAP melody composers, Johnny hit a fast pace and was soon riding the gravy train on cushions. At one time, in the fall of 1941, he had four tunes on the Hit Parade for many weeks in succession, "Blues In the Night," "Skylark," "Tangerine" and" I Remember You."

But Johnny, in high gear now as a songwriter and singer, felt that his own voice had never been recorded properly, and that his own tunes, all too often, had been waxed by artists who weren't suited to them. It kept biting him. And so, in the summer of 1942 - just five years ago-he, Glenn E. Wallichs and Buddy De Sylva formed Capitol Records, Inc.

Johnny had never enjoyed a real hit record, as a singer. But his first for the young Capitol firm, "Strip Polka," was a smash and still sells briskly today. He's had a dozen or more, since, that have topped the half-million mark. He's cletted songs that have won an Academy Award. He has become president of Capitol. He has pushed and shoved artists like Jo Stafford, Paul Weston, Andy Russell, Margaret Whiting, Freddie Slack and a dozen more to international renown with his discing methods and his tunes.