Few people are aware of it, but without prime numbers we wouldn’t have mobile phones, digital banking, or even the internet. Prime numbers allow for safe digital communication; they are the keys to our digital life. Larger prime numbers make for more complicated keys and thus safer communication. Currently, the largest known prime number consists of 27,249,425 digits. If you wanted to write it down, you’d need a book with over 9000 pages. If you happen to find an even larger number, you will be rewarded with a bounty of €150,000.

The work Semiprime consists of three layers.

The back layer (with the largest digits) shows the years of birth of the creators of Square 2.1. Combined in one specific order, they form a prime number.

The middle layer (with the medium-sized digits) is a simple conversion of the names of the creators of Square 2.1 into digits (a=1, b=2, etc.). Combined in a specific order, they too happen to form a prime number.

The front layer (with the smallest digits) is found by multiplying these two prime numbers together. Semiprimes like this are the numbers used to encrypt digital communication. The figure is too large for normal calculators, so Don Satijn spent two full days calculating it by hand. And, coincidence or not, if you read this number like a word search puzzle, all digits turn out to be part of one or more jugglable number sequences.