Find the N degrees of number 2ΒΆ

Find the value of N where N degrees of number 2
are written sequentially in a line without spaces.
def ndegrees(num):
  ans = True
  n, tempn, i = 2, 2, 2
  while ans:
    if str(tempn) in num:
      i += 1
      tempn = pow(n, i)
    else:
      ans = False
  return i - 1;

print(ndegrees("2481632"))
print(ndegrees("248163264"))

Output:

5
6