Prime Number Conversions
Check if a number is prime and find next or previous primes. Free prime number calculators for math and cryptography basics.
4 units · 3 conversions
A prime number has exactly two positive divisors: 1 and itself. Primes are building blocks of integers — every whole number factors uniquely into primes. They appear in cryptography, number theory, and competitive math.
Our tools check primality for a given integer and find the nearest primes above or below a value. Very large inputs may take longer; everyday homework-sized numbers are instant.
Popular prime number conversions
Real-world example
You need the next prime after 100 for a hashing exercise. The calculator returns 101 — confirming quickly without manual trial division.
All prime number conversions
Prime Number units explained
- Number · base unit
- Is Prime?
- Next Prime Number
- Previous Prime Number
Frequently asked questions
- Is 1 a prime number?
- No. By modern definition, primes must have exactly two distinct positive divisors; 1 has only one.
- What is the smallest prime number?
- 2 is the smallest and the only even prime number.