You have only provided a generic description. Trying to put a value on anything with just this limited information provided is difficult. Value depends on a combination of many factors. Without a detailed description to include, finish, barrel length, overall condition, stock material, sights, box, original paperwork and any accessories, only a general estimate can be given. This weapon could be in the 100-500 USD price range.
50-500 usd
100-300
Call S&W with the serial number, and they will tell you when it left the factory.
You need a gunsmith.
There is no S&W with that Model number.
110.1667
661 is prime.
This series and denomination is worth about $1 to $5 each, depending on the condition.
3√661 ≈ 8.711
661 x 1
661 x 36 = 23796
661 miles is about 1063.78 kilometres.