10 001st prime

What is the 10 001st prime number?
Largest product in a series

Find the thirteen adjacent digits in the 1000-digit number that have the
greatest product. What is the value of this product?
Special Pythagorean triplet

There exists exactly on Pythagorean triplet for which
a + b + c = 1000.
Find the product abc.
Summation of primes

Find the sum of all the primes below two million.