Check whether a number is prime and find the nearest prime numbers before and after it.
A prime number is a whole number greater than 1 that has no positive divisors other than 1 and itself. This calculator checks divisibility efficiently and also finds the closest primes on either side.
A number n is checked for divisibility by every integer from 2 up to √n - if none divide evenly, n is prime.
97 is prime - the closest primes around it are 89 (before) and 101 (after).
It tests whether the number is divisible by any integer from 2 up to its square root — if none divide evenly, it's prime.
A factor larger than the square root must have a corresponding factor smaller than it, so checking beyond that point is redundant.
No — by convention, 1 is neither prime nor composite; primes have exactly two distinct positive divisors.