Yes, you can center a number in "comma" format horizontally in a cell. Here's how:

1. Select the cell or range of cells that you want to center.
2. Click on the "Home" tab in the ribbon.
3. Click on the "Alignment" group.
4. Click on the "Align Center" button.

This will center the contents of the selected cells horizontally.

If the number is not centered after following the above steps, it may be because the cell is not wide enough to accommodate the number. In this case, you can adjust the column width by hovering your mouse over the column boundary until the cursor changes to a double-headed arrow, then click and drag the column boundary to the desired width.