What do yellow pigs and the number 17 have in common?  We aren’t sure either, but today is Yellow Pig Day and it’s a day to celebrate the unique number of 17. Join us!

Why is the number 17 so special?

Let’s first find out if 17 is prime or composite with the help of Mathletics.


17 is superior! 17 is a prime number that is truly significant in mathematics. It is the sum of the first four prime numbers – 2, 3, 5, and 7. As described in the video, a prime number is a number that can only be divided by 1 and by itself.

Did you know…

  • A 17-sided figure is called a heptadecagon.
  • In Italy, 17 is considered to be an unlucky number.
  • The fear of the number 17 is called heptadecaphobia.
  • It takes 17 muscles to smile.
  • There are 17 muscles in a horse’s ear.
  • A camel can go 17 days without water.

Why the yellow pig? It’s said that one of the creators of the day, David Kelly, had a collection of yellow pigs.  They now have a mascot for the holiday which is a yellow pig with 17 toes, 17 eyelashes and 17 teeth.

Ways to celebrate Yellow Pig Day

  • Schedule the day in increments of 17 minutes and make transitions 17 seconds
  • Complete 17 acts of kindness
  • Hand out 17 pieces of a small snack
  • Have students complete research about the number 17 and its significance in the world
  • Using an image or toy of a yellow pig to reward students, as a hall pass or even a as a ‘talking stick’