Project Euler #46 Goldbach's other conjecture

#It was proposed by Christian Goldbach that every odd composite number can be written as the sum of
# a prime and twice a square.

#9 = 7 + 2x1**2
#15 = 7 + 2x2**2
#21 = 3 + 2x3**2
#25 = 7 + 2x3**2
#27 = 19 + 2x2**2
#33 = 31 + 2x1**2

#It turns out that the conjecture was false.

#What is the smallest odd composite that cannot be written as the sum of a prime and twice a square?

def isPrime(n):
    '''check if integer n is a prime'''
    if n == 2:
        return True
    elif n < 2 or n%2 == 0:
        return False
        # range starts with 2 and only needs to go up the square-root of n
    for x in range(2, int(n**0.5)+1):
        if n % x == 0:
            return False
    return True

def isPerfectSquare(n):
    if n < 0:
        return False
    result = int(n**0.5)
    return result*result == n

odd = 9
flag = True
while flag:
    if isPrime(odd): #Exluding prime odds from test (check every odd composite number)
        odd += 2
    oddPass = False
    for i in range(2,odd-1):
        if isPrime(odd - i) and i%2 == 0 and isPerfectSquare(i/2):
            #checking if there is a number such that odd-number=prime
            #and if that number is even and number/2 is perfect square
            oddPass = True
            break
    if oddPass:
        odd += 2
    else:
        print odd
        flag = False