Answer:
The largest known prime number as of November 2020 is 2^82,589,933 - 1, a number that has 24,862,048 digits when written in base 10[1]. Before then the largest known prime number was 2^77,232,917 - 1, having 23,249,425 digits.
However, it's important to note that there is no largest prime number. As mathematician Euclid proved, there are infinitely many prime numbers. Whenever a new largest prime is discovered, an even larger one can be constructed by multiplying all the known primes together and adding 1.
Prime numbers are often used in cryptography because it is computationally difficult to factor large composite numbers into their prime factors. But the largest known primes are not actually used in cryptography, which only requires primes up to a few thousand digits. Finding large primes is more of a mathematical curiosity and a test of computing power.
The prime numbers from 1 to 100 are: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97. 2 is the only even prime number. Prime numbers continue infinitely, with the gaps between them thinning out as the numbers get larger.
