Order these numbers from least to greatest.
\[
\frac{23}{5},-\sqrt{19}, 4.56, \sqrt{21}
\]

Note that for this question you can use your mouse to drag the numbers into their positions.

Step 1 ：First, convert all the numbers into a common format to compare them. Convert all the numbers into decimal format.

Step 2 ：The fraction \(\frac{23}{5}\) can be converted into decimal by dividing 23 by 5.

Step 3 ：The square roots can be calculated using a calculator.

Step 4 ：After converting all the numbers into decimal format, compare them and order them from least to greatest.

Step 5 ：The numbers in decimal format are -4.358898943540674, 4.56, 4.58257569495584, 4.6.

Step 6 ：Order these numbers from least to greatest.

Step 7 ：\(\boxed{-\sqrt{19}, 4.56, \sqrt{21}, \frac{23}{5}}\) are the numbers in order from least to greatest.