diff --git a/X10D/Int64Extensions.cs b/X10D/Int64Extensions.cs
index 908df84..8161763 100644
--- a/X10D/Int64Extensions.cs
+++ b/X10D/Int64Extensions.cs
@@ -204,7 +204,7 @@
                 return false;
             }
 
-            long boundary = (long)Math.Floor(Math.Sqrt(number));
+            long boundary = (long) Math.Floor(Math.Sqrt(number));
             for (int i = 3; i <= boundary; i += 2)
             {
                 if (number % i == 0)
@@ -216,6 +216,41 @@
             return true;
         }
 
+        /// <summary>
+        /// Determines if the <see cref="UInt64"/> is a prime number.
+        /// </summary>
+        /// <param name="number">The number.</param>
+        /// <returns>Returns <see langword="true"/> if <paramref name="number"/> is prime, <see langword="false"/>
+        /// otherwise.</returns>
+        public static bool IsPrime(this ulong number)
+        {
+            if (number <= 1)
+            {
+                return false;
+            }
+
+            if (number == 2)
+            {
+                return true;
+            }
+
+            if (number % 2 == 0)
+            {
+                return false;
+            }
+
+            ulong boundary = (ulong) Math.Floor(Math.Sqrt(number));
+            for (uint i = 3; i <= boundary; i += 2)
+            {
+                if (number % i == 0)
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
         /// <summary>
         /// Gets an boolean value that represents this integer.
         /// </summary>