Seventeen

Seventeen (17) is the natural number following sixteen and preceding eighteen.

Seventeen is the 7th smallest prime number, and is a Fermat prime. The next prime is nineteen.

At Seventeen is a famous song by Janis Ian.

The number seventeen is used as a swearword by Swedes. The origin is controversial; though it is also known in the form "Sjutton tusen jävlär". (Seventeen thousand demons.)

In the Nordic countries the seventeenth day of the year is considered the heart and/or the back of winter.

There are exactly seventeen two-dimensional space groups. These are sometimes called wallpaper groups, as they represent the seventeen possible symmetry types that can be used for wallpaper.