4. (8 points) Numbers that can be represented in the form of the sum of consecutive natural numbers starting from 1, such as $1=1,3=1+2,6=1+2+3,10=1+2+3+4,15=1+2+3+4+5, \cdots$, are called "triangular numbers". In the 21st century (starting from the year 2000), the first "triangular number" year is $\qquad$ year.
【Solution】Solution: According to the problem, we know:
The triangular number is the sum of natural numbers.
Let the sum of natural numbers up to $n$ exceed 2000.
$$
\begin{array}{l}
\frac{1+\mathrm{n}}{2} \times \mathrm{n} \geqslant 2000 . \\
n(n+1) \geqslant 4000 .
\end{array}
$$

The product of two consecutive natural numbers is greater than 4000, so the smallest these two numbers can be is $63 \times 64=4032$. Therefore, $n=63$.
$$
\begin{array}{l}
1+2+3+\cdots+63 \\
=\frac{1+63}{2} \times 63 \\
=2016 .
\end{array}
$$

Therefore, the answer is: 2016