diff --git a/rsa.py b/rsa.py
old mode 100755
new mode 100644
index 2a0c537..1629339
--- a/rsa.py
+++ b/rsa.py
@@ -112,6 +112,12 @@ def main():
     elif sys.argv[1] == "crack":
         printHelp()
         sys.exit(1)
+    if sys.argv[1] == "is_prime" and len(sys.argv) == 4: #rsa is_prime <base> <N>
+        isPrime_cmd(0)
+        sys.exit(0)
+    if sys.argv[1] == "is_prime_mr" and len(sys.argv) == 4: #rsa is_prime_mr <base> <N>
+        isPrime_cmd(1)
+        sys.exit(0)
     if sys.argv[1] == "print" and len(sys.argv) == 3: #rsa print <key>
         printKey(readKeyFile(sys.argv[2]))
         sys.exit(0)
@@ -236,6 +242,32 @@ def verify(cipher_list):
         else: continue
     else: return None
 
+def isPrime_cmd(func):
+    number = 0
+    base = 0
+    try:
+        base = int(sys.argv[2])
+    except ValueError as e:
+        print(f'Value {sys.argv[2]} is not a valid base (2, 8, 10, 16)',
+              file=sys.stderr)
+
+    try:
+        number = int(sys.argv[3], base)
+    except ValueError as e:
+        print(f'Value {sys.argv[3]} is not valid for as a base {base} number',
+              file=sys.stderr)
+    
+    if func == 0:
+        prime = isPrime(number)
+    elif func == 1:
+        prime = mr.is_prime(number)
+
+    if prime:
+        print('Prime')
+        print(number)
+    else:
+        print('Not prime')
+    
 def readKeyFile(keyName):
     key = tuple()
     with open(keysFolder+keyName, "r") as keyFile: