6+6+6+6=20
181
two
I'm sure there are more than 2 prime numbers that are 400 digits long.
1348.
Two (or four) digits added together cannot equal 42. Two-digit numbers multiplied together cannot equal 82.
I believe here are 51 such numbers.
181
6+6+6+6=20
181
8 and 14
two
Odd numbers. I presume you mean won't split into two equal parts. There are no numbers apart from one that won't split into two exactly.
No two numbers that can be completely written down with digits can be added, subtracted, multiplied, or divided to equal PI. If they could be divided to equal PI, then PI would be a rational number. But it isn't.
I'm sure there are more than 2 prime numbers that are 400 digits long.
1348.
13.574813431681335 and 16.574813431681335 Also -13.574813431681335 and -16.574813431681335