Fresh from a recent world tour that took him back to his native Russia for the first time in 61 years, pianist Vladimir Horowitz arrived at the White House yesterday to receive his latest honor, the Medal of Freedom.

President Reagan hailed the 81-year-old Horowitz as "the most dazzling virtuoso since Liszt set the standard in the 19th century."

Nancy Reagan placed the emblem and its ribbon of heavy cloth around the pianist's neck, and followed it with a kiss.

The president also acclaimed Horowitz, an American citizen since the early '40s, as "an ambassador of good will to the people of the Soviet Union."

Aglow with smiles and customarily dapper in polka-dot bow and matching handkerchief, Horowitz was accompanied at the ceremony and reception by his wife Wanda Toscanini Horowitz, the daughter of the man widely regarded as the century's most important conductor.

In his remarks, the president said Horowitz's televised concert in the Soviet Union had "reminded us of the common humanity of all peoples," and he recalled the comment of a British critic that Horowitz's playing was that of the greatest pianist alive.

The Medal of Freedom citation for Horowitz read: "He has said it remains the purpose of his life to bring meaning to music each time he plays. With masterful technique, consummate musicianship, and profound humanity, Vladimir Horowitz brings not only meaning to music, but joy and beauty and meaning to our lives. This adopted son of America, the last of the great romantics as he is sometimes called, is more than a national treasure, he is a treasure to people the world over.