Hexakosioihexekontahexaphobia

Hexakosioihexekontahexaphobia is the fear of the number 666. The name is built from the Greek words for “six hundred sixty-six,” hexakosioi hexekonta hex, with -phobia on the end. Wikipedia: Number of the beast At 29 letters, it’s one of the longest phobia names you’ll come across.

You can say it in chunks: hex-ah-koh-see-oy, hex-eh-kon-tah, hex-ah-FOH-bee-uh. That’s “six hundred,” “sixty,” “six,” and “fear.”

It isn’t a diagnosis. Most people meet the word on lists of strange phobias. But the fear behind it is real for some people, and there are well-documented cases of people going out of their way to avoid 666. That’s why we class it as a rare or disputed term rather than a joke.

Why is 666 scary?

The number comes from the Book of Revelation in the Bible. Chapter 13, verse 18 gives 666 as the “number of the beast.” Wikipedia: Number of the beast For many Christians it’s tied to evil and the end times, so the fear can be religious more than superstitious. It isn’t the only fear word with religious roots. Papaphobia, the fear of the pope, has been in English dictionaries since at least 1828.

There’s a twist. Some of the oldest surviving manuscripts of Revelation give the number as 616 instead. A papyrus fragment about 1,700 years old, studied at Oxford around 2005, has 616, and some scholars think that was the original. Wikipedia: Number of the beast

Many horror and doomsday films also use 666 as a mark of evil or the end of the world. Cleveland Clinic: Arithmophobia

Real cases of avoiding 666

People, governments, and companies have changed numbers to get away from 666. Wikipedia’s article on the number of the beast lists several examples. Wikipedia: Number of the beast

• In 1989, Nancy and Ronald Reagan had the address of their new Los Angeles home changed from 666 St. Cloud Road to 668.
• In 2003, US Route 666 in New Mexico was renumbered as US Route 491.
• In 2013, a high school runner in Kentucky refused to race in a regional meet after drawing bib number 666.
• In 2015, a US congressman had a bill renumbered from 666 to 702.
• In 2021, the Manhattan office tower at 666 Fifth Avenue was renumbered 660.

A more recent story comes from Poland. A bus route to the seaside town of Hel ran as line 666 for years and became a tourist draw. In 2023, after protests from some Christian groups, the operator renumbered it 669. The Guardian Wikipedia notes that another company brought the 666 route number back in 2026 as a publicity stunt. Wikipedia: Number of the beast

Some of these choices may reflect real fear. Others were about avoiding complaints or bad publicity. A renamed road isn’t proof that anyone had a phobia.

How it fits with other number fears

Fear of 666 belongs to a wider family. Cleveland Clinic lists it alongside fear of 4 and fear of 13 as examples of fearing specific numbers, often for religious or superstitious reasons. Cleveland Clinic: Arithmophobia

• Tetraphobia is the fear of the number 4, common in parts of East Asia.
• Triskaidekaphobia is the fear of the number 13.
• Arithmophobia is the broader fear of numbers, either all of them or particular ones.

What sets 666 apart is how specific its source is. Thirteen’s bad luck has many stories behind it. 666 points back to one verse.

Fear or phobia?

Noticing 666 on a receipt and feeling a small chill is common. A specific phobia is different: it’s a marked, lasting fear that’s out of proportion to the danger and leads to avoidance or strong distress. APA Dictionary of Psychology

With 666, signs of a problem might include refusing a phone number, house, or ticket because of the digits, feeling real panic when the number appears, or spending a lot of time checking for it. Our fear versus phobia guide explains the difference in more detail.

What can help?

If fear of 666, or of numbers in general, is causing real distress, the treatments used for other phobias may help. The NHS lists talking therapies such as cognitive behavioral therapy (CBT). NHS: Phobias For number fears, Cleveland Clinic describes exposure therapy, where you work up slowly to facing the number, often starting by imagining it. Cleveland Clinic: Arithmophobia

When the fear has religious roots, it can also help to talk with a faith leader you trust. A therapist can work alongside your beliefs; you don’t have to give them up to feel less afraid.

If checking for the number has turned into rituals you feel you must do, mention that to a doctor too, since it may point to a different kind of anxiety problem.

Frequently asked questions

How many letters are in hexakosioihexekontahexaphobia?

It has 29 letters. For comparison, hippopotomonstrosesquipedaliophobia, the joke word for the fear of long words, has 35. See our page on hippopotomonstrosesquipedaliophobia. Word lovers have made other self-mocking phobia names too. Aibohphobia, the fear of palindromes, reads the same backwards.

Why does the word have “hex” in it three times?

Because 666 has three sixes. The Greek words are hexakosioi (600), hexekonta (60), and hex (6). Wikipedia: Number of the beast

Is fear of 666 the same as fear of Friday the 13th?

No. Fear of Friday the 13th is about a date, and fear of 13 is triskaidekaphobia. Fear of 666 is about one number linked to a Bible verse. Some people have both.

Has anyone actually changed a number because of 666?

Yes. Examples include the Reagans’ Los Angeles address, a US highway in New Mexico, and a Polish bus line to Hel. Wikipedia: Number of the beast

When to get help

Talk to a doctor or therapist if fear of 666 or other numbers is driving your choices, causing panic, or taking up a lot of your day. You don’t need to use the long word. “Certain numbers make me very anxious and it’s affecting my life” is enough. More odd names and their meanings are in our guide to the strangest named phobias.