Project Euler #92 Square digit chains

#A number chain is created by continuously adding the square of the digits in a number to form a new number
# until it has been seen before.

#For example,

#44 > 32 > 13 > 10 > 1 > 1 (44 is called a happy number)
#85 > 89 > 145 > 42 > 20 > 4 > 16 > 37 > 58 > 89

#Therefore any chain that arrives at 1 or 89 will become stuck in an endless loop.
# What is most amazing is that EVERY starting number will eventually arrive at 1 or 89.

#How many starting numbers below ten million will arrive at 89?

def isUnHappy(n):
    """ Assumes n an int > 0
    """
    if n == 89:
        return True
    elif n == 1:
        return False
    nStr = str(n)
    digitsSqrSum = 0
    for digit in nStr:
        digitsSqrSum += (int(digit))**2
    return isUnHappy(digitsSqrSum)



count = 0
for i in range(1,10000000):
    if isUnHappy(i):
        count += 1
print count