Pi Spigot Algorithm + Primality Check + Palindrome Check

pi.py

#naive implementation of a pi spigot algorithm
def gen_pi(n):
  q, r, t, k, m, x = 1, 0, 1, 1, 3, 3
  for j in range(n):
    if 4 * q + r - t < m * t:
      yield m
      q, r, t, k, m, x = 10*q, 10*(r-m*t), t, k, (10*(3*q+r))/t - 10*m, x
    else:
      q, r, t, k, m, x = q*k, (2*q+r)*x, t*x, k+1, (q*(7*k+2)+r*x)/(t*x), x+2

def isPrime(number):
  if number == 4:
    return False
  elif number in [1,2,3]:
    return True
  else:
    return all(number % i for i in xrange(2, number/2))

def arePrime(list):
  return all(isPrime(i) for i in list) 

def isPalindrome(list):
  j, k = 0, len(list) - 1

  if len(list) in [0,1]:
    return True
  elif len(list) == 2:
    return list[0] == list[1]
  elif len(list) % 2 == 1:
    while j != k:
      if list[j] != list[k]:
        return False
      else:
        j, k  = j+1, k-1
  else:
    while j > k:
      if list[j] != list[k]:
        return False
      else:
        j,k = j+1, k-1

  return True 

def findDigits():
  rolling = []
  for i in gen_pi(1000000):
    rolling.append(i)

    if len(rolling) > 7:
      rolling.pop(0)
     
    if len(rolling) == 7 and isPalindrome(rolling) and isPrime(int(listAsString(rolling))):
      return rolling

def listAsString(list):
  return "".join([str(digit) for digit in list]) 

print listAsString(findDigits())