Hunting Million-Digit Primes from My Loft

He spent 24 years hunting giant hidden numbers, and commenters want a better scoreboard

TLDR: A solo number-hunter says his home computers have found eight giant prime numbers, including one with 1.3 million digits. Commenters were charmed by the old-school volunteer-computing vibe but immediately started grumbling that the project’s website tracker seems wrong.

A hobby project in a loft has somehow turned into a 24-year slow-burn obsession: one person, a pile of ordinary computers, and a mission to find gigantic prime numbers no one had ever seen before. The wildest part? His biggest win — a number over 1.3 million digits long — wasn’t discovered in some movie-style eureka moment. A machine quietly found it at 1 a.m., moved on, and he only noticed later. Honestly, that anticlimax is half the charm.

But the real energy comes from the crowd. The strongest reaction is pure nostalgia: commenters instantly compared it to BOINC, the old volunteer-computing scene where people let their home PCs help with science overnight. One user basically summed up the mood as, please, can we have that internet back? There’s a cozy, slightly chaotic romance to this whole thing: second-hand machines, summer heat in the loft deciding what stays online, and a tiny community keeping a weird corner of computing alive.

And then came the mini-drama. Right after saying it looked fun, the same commenter took a swing at the website tracking, complaining that a switched-off machine still showed as Active and kept racking up time. So yes, even in a wholesome story about giant numbers, the comments found a way to become a product-feedback battlefield. The vibe is basically: love the nerdy dream, fix the dashboard. It’s equal parts admiration, bug report, and a little "dad, your homemade supercomputer is lying to me" energy.

Key Points

  • The author has spent 24 years searching for primes of the form k·2^n − 1 on ordinary hardware, beginning in 2001.
  • The distributed system primecrunch has recorded primes since February 2016 and now contains 73,121 confirmed primes.
  • Eight primes found through the system have more than one million digits; the largest is 1007·2^4332776 − 1 with 1,304,299 digits.
  • The project runs on modest infrastructure, including two second-hand Intel i5 servers, a Postgres database host, and about ten compute machines.
  • Sieving removes most composite candidates before expensive primality testing: from about 22 billion candidates, only 633 million survive to full testing.

Hottest takes

"i wish there was more boinc" — sudo_cowsay
"turned off my machine but it is still saying 'Active'" — sudo_cowsay
"the compute time keeps increasing" — sudo_cowsay
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