Aperture values are fractions. They are often writen as F/x. An aperture value of 2 is actually 1/2, an aperture value of 22 is actually 1/22. An aperture of F/2 is wider (larger) than F/22. Just like a piece of pie, 1/2 is a larger than 1/4.
Choosing a smaller aperture (higher F number) may not always result in a sharper image. As the aperture size decreases you may find that the overall image loses clarity. This is due to the occurance of diffraction particularly noticable with smaller apertures. You can see in the below image the bottom chain at F/32 is not as sharp as it is at F/16.