A prime number cannot be divided evenly by any number except 1 and itself — the largest known has 24 million digits

Pi has been calculated to over 100 trillion digits — but 39 digits is enough to measure the observable universe to the width of a hydrogen atom

Pi's 39-digit approximation measures universe's width to hydrogen atom's size

Benford's law: in natural datasets, the leading digit is 1 about 30% of the time, not 11%

Benford's law: Leading digit in natural datasets, 1: 30%

The number 1729 is the Hardy-Ramanujan number — the smallest expressible as the sum of two cubes in two ways

1729: smallest integer expressible as sum of two cubes in two distinct ways

There are more possible arrangements of a deck of cards than atoms on Earth — 52! ≈ 8 × 10^67

Card arrangements vastly exceed Earth's atoms: 52! ≈ 8 × 10^67

The Caspian Sea is the world's largest lake — technically not a sea despite the name

The Caspian Sea is the world's largest inland body of water, not a sea

The birthday paradox: in a group of 23 people, there's a 50% chance two share a birthday

In a group of 23, there's a 50% chance at least two share a birthday due to the birthday paradox