Yellow Pig Day

Yellow Pig Day is celebrated each year on July 17 and is dedicated to the number 17. This quirky and delightful holiday originated with two mathematicians who had a deep fascination with the number and decided to pair it with an equally eccentric symbol—a yellow pig. Whether you love math or just enjoy unusual holidays, Yellow Pig Day is the perfect excuse to have some fun with numbers.

History

Yellow Pig Day began in the mid-20th century, created by mathematicians David Kelly and Michael Spivak during their studies of number theory. While it’s unclear why they were so fascinated by the number 17 specifically, it became the centerpiece of this humorous celebration. They invented the concept of a yellow pig with 17 eyelashes, which has since become the quirky mascot of the holiday. At first glance, the idea might seem random, but the number 17 has many fascinating appearances throughout history, science, and culture.

Interesting Facts

• The number 17 appears 13 times in the Bible.
• Some view 17 as a symbol of the French Revolution, since the year 1789 contains the digits 1 and 7, and 8 + 9 = 17.
• Tutankhamun’s mummy was wrapped in 17 layers of linen before burial.
• Rome’s Pantheon has 17 columns in its portico.
• In Italy, 17 is considered unlucky. The Roman numeral XVII is an anagram of “VIXI,” which means “I lived” in Latin—implying death.
• The fear of the number 17 is called heptadecaphobia.

How to Take Part

Celebrate Yellow Pig Day by embracing your inner math nerd. Draw yellow pigs, solve math puzzles, and keep an eye out for the number 17 throughout your day. Whether it’s in dates, addresses, or prices, 17 is everywhere once you start looking. Share your favorite yellow pig artwork or trivia on social media using the hashtag #NationalYellowPigDay.

When is Yellow Pig Day in 2025?

Yellow Pig Day is observed on July 17 each year.

Observations