There is no president with the initials AJ.
Ronald Wilson Reagan (1911-2004) ... The 40th President of the US
There were 40 presidents from 1789 to 1990. (Grover Cleveland served twice, I count him one; counting this way, George Bush was the 40th, who had started his term 1989.)
Harry Truman. The S. didn't stand for anything.
The 26th presidents full name was Theodore Roosvelt Jnr. He was also known as TR or Teddy. He had no middle name, so he had only one initial: T for Theodore.
Herbert Hoover is the only president to have the initials HH. He was the 31st president of the United States and served from march 4, 1929 to march 4, 1933. The Hoover Dam in Nevada bears his name.
Your question is in the category of John F. Kennedy. But in case you still weren't sure, it stands for John Fitzgerald Kennedy.
40th = fortieth.
Yes, St. Louis, Missouri is located approximately at 38.63 degrees north latitude, which is slightly below the 40th parallel.
The 40th multiple of 15 are 600.
40th birthday
No US president has I, ,X, Y , or Z among his initials.