As of August 2017, the largest known Prime number is 2^74,207,281 − 1, a number with 22,338,618digits.
I attached a link with the 100 largest known prime numbers, there you can see the number of digits.
999,983
As of August 2017, the largest known prime number is 2^74,207,281 − 1, a number with 22,338,618digits.
It has been proven that there is no largest prime number, and therefore there exists a prime number, in fact, infinitely many, greater than 10^999999999 (having a billion digits); however, no humans have actually found a specific number of that size and identified it as prime.
The number 11 is prime and has two identical digits.
773.
The largest prime number that has 4 digits and begins with a 1 is 1,999.
73 is the largest two-digit number that is prime and has prime numbers for both of its digits.
73 is the largest 2 digit number that is both prime and has prime numbers for both of its digits.
The largest 3 digit number whose digits are all primes is 777. The largest 3 digit number with different prime digits is 753.
Numbers never end. Thus it is impossible to find the largest prime number. The largest known prime number as of 2003 is m39 = 213,466,917-1 It has 4,053,946 digits and does not fit in this box.
999,983
4,053,946
The largest three digit prime number whose digits are all primes is 773.
As of January 2017 , the largest known prime number is 2^74,207,281 − 1, a number with 22,338,618 digits.
As of October 2015, the largest known prime number is 2^57,885,161 − 1, a number with 17,425,170 digits.
17,425,170 digits
As of January 25, 2014, the largest known prime number was calculated to be 257,885,161 − 1; a number containing 17,425,170 digits. This is, of course, too large to display.