The Number 67: Prime, Lucky and Now Famous

The number had a life before TikTok. Here is what mathematicians, physicists and trivia hosts already knew about 67.

It is prime

67 cannot be divided by anything but 1 and itself. It sits between the primes 61 and 71, and it is the 19th prime number. Which means that, technically, the meme is about an indivisible thing, which is more poetic than anyone intended.

It is an "irregular" prime

A category from number theory with a long story behind it. The short version: 67 misbehaves in a specific way that made it interesting to people working on Fermat's Last Theorem a hundred years before it was proved. Some numbers are famous for being neat. 67 is famous, in maths, for being difficult.

It is a lucky prime

There is a sieve, invented in the 1950s, that removes numbers from a list in a pattern; the survivors are called "lucky numbers". 67 survives, and it is also prime, so it is a "lucky prime". This has no practical use and we have never been happier to report a fact.

In science

• Holmium is element 67 on the periodic table. It has the strongest magnetic properties of any element. We are not saying anything. We are just saying.
• The Heisenberg-era physicist Ernst Ising was born in 1900; his model has nothing to do with 67 and we have nothing further to add.
• 67P is the comet that the Rosetta mission landed a probe on in 2014. The first time humanity landed on a comet, it was a 67.

In sport

• Six feet seven inches is the height of a great many basketball players and the reason you are here.
• 67 is a common par-breaking round in golf, a big innings in cricket, and a scoreline that makes college gyms explode.

In everyday life

• Route 67 runs through the American Midwest.
• 6:07 happens twice a day.
• The 67th day of the year is March 8, unless it is a leap year, in which case the meme has to wait a day.

The moral

Every number is interesting if you look. 67 just made everybody look.