ProjectEuler#10 Summation of primes

#The sum of the primes below 10 is 2 + 3 + 5 + 7 = 17.

#Find the sum of all the primes below two million.

#isPrime algorithm for MIT 6.00x course notes

def isPrime(n):
    '''check if integer n is a prime'''
    # 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

acc = 5 #sum of primes 2 and 3
for i in range (5, 2000001,2): #loop over odd number

    if i%3 != 0 and isPrime(i): #check if number not divisible by 3 then check isPrime
        acc += i

print acc