11. Among the following 4040 numbers:
$1,2, \cdots, 2020,1^{2}, 2^{2}, \cdots, 2020^{2}$, the median is ( ).
(A) 1974.5
(B) 1975.5
(C) 1976.5
(D) 1977.5
(E) 1978.5
11. C.

Since $44^{2}=1936, 45^{2}=2025$, therefore, after sorting these 4040 numbers, $1^{2}, 2^{2}, \cdots, 44^{2}$ are before 1937, and $45^{2}, \cdots, 2020^{2}$ are after 2024. This indicates that the 1981st number is 1937, the 2020th number is 1976, and the 2021st number is 1977. Thus, the median is 1976.5.