Call S&W with the serial number, and they will tell you when it left the factory.
50-500 usd
100-300
There is no S&W with that Model number.
You need a gunsmith.
110.1667
661 is prime.
This series and denomination is worth about $1 to $5 each, depending on the condition.
661 x 1
3√661 ≈ 8.711
661 x 36 = 23796
661 miles is about 1063.78 kilometres.