getting the range of a number column(min/max) if there are missing numbers in between

How would I query the range of a number column if the number ends somewhere then picks up again at a higher number?

If I had a column like:

Number
-------
 1
 2
 3
 4
 5
 11
 12
 13

How can I return a result like

Min | Max
----------
 1  |  5
 11 |  13