January 2019 Fiendish Function

The Fiendish Function posed during January 2019 had the following sample guesses and replies:

• GUESS
• REPLY
• 1
• 1
• 2
• 2
• 3
• 6
• 4
• 42
• 5
• 21
• 10
• 88263

The rule was: "Take the factorial of the number, then reverse the order of the digits".

Suppose the guess was 12:

• Find 12 x 11 x 10 x 9 x 8 x 7 x 6 x 5 x 4 x 3 x 2 x 1, giving 479001600.
• Reverse the order of the digits, giving 6100974.

So the result is 6100974.