You can not generally change a digit in a number to make it prime. That is not how that works.
To prove this number is prime, you would have to run an algorithm on it. In Python or Matlab you could invoke the method "isprime()" and input this number. However, this number is much bigger than any 64-bit integer. I am aware of libraries that can calculate with numbers contained in strings, which makes it possible to work with 1800 digit numbers, but it would be rather slow in comparison.
I think your best hope to prove this is real is to look into existing databases of prime numbers. The largest prime number found so far has almost 25 million (!) digits.
I could have a look at some Python code and run some algos to see if this 1800 digit is truly a prime number.
Also: "To find whether a larger number is prime or not, add all the digits in a number, if the sum is divisible by 3 it is not a prime number. Except 2 and 3, all the other prime numbers can be expressed in the general form as 6n + 1 or 6n - 1, where n is the natural number."
The sum of the digits is 3430, which is not divisible by 3, meaning the number might be a prime.
You can not generally change a digit in a number to make it prime. That is not how that works.
To prove this number is prime, you would have to run an algorithm on it. In Python or Matlab you could invoke the method "isprime()" and input this number. However, this number is much bigger than any 64-bit integer. I am aware of libraries that can calculate with numbers contained in strings, which makes it possible to work with 1800 digit numbers, but it would be rather slow in comparison.
I think your best hope to prove this is real is to look into existing databases of prime numbers. The largest prime number found so far has almost 25 million (!) digits.
I could have a look at some Python code and run some algos to see if this 1800 digit is truly a prime number.
Also: "To find whether a larger number is prime or not, add all the digits in a number, if the sum is divisible by 3 it is not a prime number. Except 2 and 3, all the other prime numbers can be expressed in the general form as 6n + 1 or 6n - 1, where n is the natural number."