Timing five isprime functions (Python)

''' timeit_isprime.py
check the speed of five isprime functions
tested with Python34   by  vegaseat (dns)  16may2015
'''

import timeit
import sys

print(sys.version)

def isprime2(n):
    '''
    check if integer n is a prime, return True or False
    '''
    # 2 is the only even prime
    if n == 2:
        return True
    # integers less than 2 and even numbers other than 2 are not prime
    elif n < 2 or not n & 1:
        return False
    #if n % 3 == 0: return False
    # loop looks at odd numbers 3, 5, 7, ... to sqrt(n)
    for i in range(3, int(n**0.5)+1, 2):
        if n % i == 0:
            return False
    return True

def isprime3(n):
    '''
    check if integer n is a prime, return True or False
    '''
    # 2 is the only even prime
    if n == 2:
        return True
    # integers less than 2 and even numbers other than 2 are not prime
    if n < 2:
        return False
    if not n & 1:  # even numbers
        return False
    # loop looks at odd numbers 3, 5, 7, ... to sqrt(n)
    for i in range(3, int(n**0.5)+1, 2):
        if n % i == 0:
            return False
    return True

def isprime4(n):
    '''
    check if integer n is a prime, return True or False
    uses a while loop, another way to write it, but is slower
    '''
    # 2 is the only even prime
    if n == 2:
        return True
    # integers less than 2 and even numbers other than 2 are not prime
    if n < 2:
        return False
    if n % 2 == 0:  # even numbers
        return False
    k = 3
    while k * k <= n:
         if n % k == 0:
             return False
         k += 2
    return True

def isprime5(n):
    # deal with low primes and even numbers
    if n in (2,3,5,7,): return True
    if n < 2 or n%2 == 0: return False
    if n%3 == 0: return False
    # need divisors only up to sqrt(x) or n**0.5
    sqr = int(n**0.5)
    div = 5
    while div <= sqr:
        if n%div == 0: return False
        if n%(div+2) == 0: return False
        # loop every 6th integer
        div += 6
    return True

def isprime6(n):
    # no negative numbers
    n = abs(n)
    # deal with primes under 5
    if n in (2,3,):
        return True
    # the rest of the primes are multiples of 6 plus or minus 1
    # this eliminate 2/3 of the remaining candidates
    if (n < 5) or ((n % 6) not in (1, 5,)):
         return False
    # need divisors only up to math.sqrt(x)+2 (same as n**0.5+2)
    for div in range(6, int(n**0.5+2), 6):
        if (n % (div+1) == 0) or (n % (div-1) == 0):
            return False
    return True

# note 9999991 is a prime number, use for testing
print("isprime2(9999991) = {}".format(isprime2(9999991)))
print("isprime3(9999991) = {}".format(isprime3(9999991)))
print("isprime4(9999991) = {}".format(isprime4(9999991)))
print("isprime5(9999991) = {}".format(isprime5(9999991)))
print("isprime6(9999991) = {}".format(isprime6(9999991)))


stmt = 'isprime2(9999991)'
find_function = 'from __main__ import isprime2'
t = timeit.Timer(stmt, setup=find_function)
# doing 1000 passes * 1000 gives the time in microseconds/pass
elapsed = (1000 * t.timeit(number=1000))
print("%s takes %0.3f micro-seconds/pass" % (stmt, elapsed))

stmt = 'isprime3(9999991)'
find_function = 'from __main__ import isprime3'
t = timeit.Timer(stmt, setup=find_function)
# doing 1000 passes * 1000 gives the time in microseconds/pass
elapsed = (1000 * t.timeit(number=1000))
print("%s takes %0.3f micro-seconds/pass" % (stmt, elapsed))

stmt = 'isprime4(9999991)'
find_function = 'from __main__ import isprime4'
t = timeit.Timer(stmt, setup=find_function)
# doing 1000 passes * 1000 gives the time in microseconds/pass
elapsed = (1000 * t.timeit(number=1000))
print("%s takes %0.3f micro-seconds/pass" % (stmt, elapsed))

stmt = 'isprime5(9999991)'
find_function = 'from __main__ import isprime5'
t = timeit.Timer(stmt, setup=find_function)
# doing 1000 passes * 1000 gives the time in microseconds/pass
elapsed = (1000 * t.timeit(number=1000))
print("%s takes %0.3f micro-seconds/pass" % (stmt, elapsed))

stmt = 'isprime6(9999991)'
find_function = 'from __main__ import isprime6'
t = timeit.Timer(stmt, setup=find_function)
# doing 1000 passes * 1000 gives the time in microseconds/pass
elapsed = (1000 * t.timeit(number=1000))
print("%s takes %0.3f micro-seconds/pass" % (stmt, elapsed))


''' result ...
3.4.2 |Continuum Analytics, Inc.| (default, Oct 21 2014, 17:42:20) 
[GCC 4.2.1 (Apple Inc. build 5577)]
isprime2(9999991) = True
isprime3(9999991) = True
isprime4(9999991) = True
isprime5(9999991) = True
isprime6(9999991) = True
isprime2(9999991) takes 162.309 micro-seconds/pass
isprime3(9999991) takes 162.340 micro-seconds/pass
isprime4(9999991) takes 280.765 micro-seconds/pass
isprime5(9999991) takes 135.013 micro-seconds/pass
isprime6(9999991) takes 127.583 micro-seconds/pass

'''