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.
Business strikes 273,304,004 Proof 3,950,762
All half-dollars minted from 1964 to the present bear an image of John F Kennedy.
1964 US nickels were minted at Philadelphia (no mint mark at that time) and Denver ("D")
A 1963 JFK half would be a spectacular find because none were minted. His picture was put on the half dollar in 1964.
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%
Yes, some 1964 Kennedy half dollars are worth more than others, particularly those that were minted in San Francisco (marked with an "S") or those that are in particularly high grades, such as uncirculated or proof conditions. Additionally, coins with errors or unique characteristics can also command higher prices. Generally, the standard 1964 Kennedy half dollar is worth around its face value in circulated condition, but specific variations can significantly increase in value.
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.