There are four pair of mirror primes.
There 25 primes less than 100: 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.
There are 5,761,455 primes less than 100,000,000. The largest of which is 99,999,989.
All pairs of two primes are coprime. There are fifteen primes under 50. So that means there are 105 unique pairs of "coprime primes", or more generally, pairs of primes, under 50.
One pair of twin primes between 135 and 145
A boatloadThere are in infinite number or primes, and they are still being discovered. The people who discover the prime that has more than 10 million digits will win $100,000. I'm pretty sure they're getting close, something like 9.8 million digits.
An n-digit number has 4^n such numbers.
There are four pair of mirror primes.
As there are infinitely many primes (as Euclid proved circa 300 BC) and not all of them are (or can be) known, it is impossible to answer this question.
The first few Fibonacci primes are 2, 3, 5, 13, 89. Fibonacci primes with thousands of digits have been found but it is not known whether there are infinitely many (Wikipedia, see link).
Pigeons do not have digits like fingers or toes. Instead, they have claws on their feet, typically four on each foot.
Expressed in figures, this is equal to 93,000,000. This is eight digits, including six zeroes.
there are 13 primes not 5.
21.
There are only 2 primes in 80: 2 and 5.
There are 169 primes that are smaller than 1000.
21