Business strikes 273,304,004
Proof 3,950,762
156,205,446 struck at Denver Mint.
The Denver Mint made less coins.
They were minted at Philadelphia, Denver and San Francisco. They were minted in 1964.
All half-dollars minted from 1964 to the present bear an image of John F Kennedy.
A 1963 JFK half would be a spectacular find because none were minted. His picture was put on the half dollar in 1964.
1964 US nickels were minted at Philadelphia (no mint mark at that time) and Denver ("D")
The last half dollars that carried a picture of Miss Liberty were minted in 1947. All halves minted since 1964 have a picture of John F. Kennedy and are called Kennedy halves. There's more information at the Related Question.
They're not made of anything because the first Kennedy halves weren't struck until 1964.On the other hand, 1963 FRANKLIN half dollars are made of 90% silver and 10% copper.
1964: 90% 1965-70: 40% 1971-present: 0%
Kennedy half-dollars minted 1965-1970 are 40% silver, so those are worth something. Then certain Eisenhower dollars minted in San Francisco also contain silver, but those were never released into circulation, but rather sold to collectors.
1964, the year after Kennedy died.
Kennedy half dollars (50 cent pieces) have only been minted since 1964. And in any case, JFK was only 5 years old in 1922 and on top of that the U.S. didn't mint ANY half dollars in 1922.