160 GB drive showing capacity of only 31.9 GB

I have a Western Digital 160 GB/Go USB portable hard drive (P/N: WDBAAR1600ABK-00). I’ve noticed recently when I look at “Properties” for this drive, the capacity is shown as 31.9 GB, far from the 160 GB that my drive should be. I’m using the drive on a new system with Windows 10 Pro.

Is there some reason the capacity is shown as only 31.9 GB? Is there anything I can do to obtain a capacity of something much closer to the 160 GB?