Four amines: 1-propanamine; N-methylethanamine or ethylmethylamine; isopropylamine or 2-propanamine; trimethylamine.
I reasoned in this way:
The formula belongs to a saturated molecule (there is the maximum number of hydrogen atoms, then no ring or multiple bonds are possible).
If you ignore the difference between carbon and nitrogen, there are four atoms that you can arrange all four in linear way or only three linearly, and the fourth atom linked to the centre as a side branch. There are not other possibilities. Let's call Z structure the first type and Y type the second.
Now let's place the N atom into the Z type structure: you can choose to put N at one end or in the middle, in one of the two equivalent positions. In the first case you get 1-propanamine, in second case you get N-methylethanamine or ethylmethylamine.
Finally, let's place the N atom into the Y structure. You have once again two choices: in one of three equivalent ends or in the centre. In the first case you get isopropylamine or 2-propanamine; in the second you get trimethylamine.
Here is a sketch image of the four amines created with MolVIew.org
I hope this would be helpful.