Does versionName have to be increasing?

I had uploaded these versions of my app to Google Play:

VersionCode             VersionName
       1                      1
       2                      2
       3                      3
       …
       15                     15

Now I plan to upload the version with

versionCode: 16
versionName: 1.6.1

Is this versionName allowed? (Or do I have to choose 16.1, so that versionNames are non-decreasing).

via Chebli Mohamed