67 is the most searched number on Google (instead of the naughty old favourite, 69). 

Why? For the Generation Alpha folks (who drive up the popularity of 67), it means …. well, nothing.  The phrase “6-7” first appeared in the 2024 rap track Doot Doot (6 7) by Philadelphia rapper Skrilla. It didn’t mean anything specific, but its catchy rhythm made it stick. 

So 67 becomes the internet’s favourite number not because of math, but because it embodies the playful, viral, and community-driven way Gen Alpha communicates today. 

But for the mathematician in me, 67 is the exponent in the Mersenne number 267−12^{67} – Mersenne primes are central in cryptography and digital security, making 67 a gateway to massive structures hidden in a single exponent.

Marsenne Primes

A Mersenne prime is a very special kind of prime number. It looks like this:

2n−12^n – 1That means you take 2, raise it to some power, and subtract 1. Sometimes the result is prime, sometimes it isn’t. When it is prime, it’s called a Mersenne prime.

Why They’re Beautiful

• Simplicity: They come from the simplest building block in math — the number 2.
• Elegance: Written in binary, they’re just strings of 1s.
• Rarity: Not every 2n−12^n – 1 is prime. Finding one is like discovering a rare gem hidden in a mountain of ordinary rocks.
• Infinity mystery: We don’t know if there are infinitely many Mersenne primes. That open question makes them feel like a treasure hunt with no end.
• Connection to giants: The largest primes humans have ever found are Mersenne primes, with millions of digits. They’re mathematical skyscrapers built from the simplest recipe.

But take away the maths stuff, Mersenne primes are beautiful because they show how simplicity can give rise to grandeur. From the humblest number, 2, we get rare, towering primes that connect deep mathematics with elegance, mystery and wonder.

Lego blocks and cathedrals

Think of Mersenne primes like cathedrals made of Lego bricks:

• The Lego brick is just “2.”
• Stack them in a certain way (powers of 2 minus 1), and suddenly you get a cathedral that’s both simple and breathtaking.
• Most stacks collapse into ordinary numbers, but once in a while, the structure stands tall and perfect — that’s a Mersenne prime.

A cryptography