Printing octo-thorpes
Python's str has justifying functions. The relevant one here would be rjust(). So we could just use that directly:

def hash_print(number):
    for i in range(number):
        hashes = '#' * (i+1)
        print hashes.rjust(number)


This is also \$O(n^2)\$ to build up hashes over time, so on the off chance that performance becomes a consideration, we could build it up as we go:

def hash_print(number):
    hashes = [' '] * number
    for i in range(number):
        hashes[number - i - 1] = '#'
        print ''.join(hashes)