Mathematics
What is Prime numbers?
A prime number is a whole number greater than 1 that has exactly two factors: 1 and itself. 2, 3, 5, 7, and 11 are primes — they're the building blocks of all other numbers.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains prime numbers.
Key things to understand
- 1A prime can't be divided evenly by any number except 1 and itself.
- 22 is the only even prime; every other even number is divisible by 2.
- 3Every whole number factors uniquely into primes (the fundamental theorem of arithmetic).
- 4Primes power the modern encryption that secures the internet.
Frequently asked questions
- Is 1 a prime number?
- No. A prime has exactly two distinct factors, and 1 has only one factor.
- Why are prime numbers important?
- They're the building blocks of all integers and underpin encryption that keeps online data secure.
- How many prime numbers are there?
- Infinitely many — a fact proven by Euclid over 2,000 years ago.