Chinese Unknouwn coin. [gelöst]

This coin have 22 milimiters.

Thanks 

Qian Long 1774

The holder already gives half of the answer, emperor Qianlong. Meaning we only have to look at the reverse.

After that, we have N#19755 .

But, after a second look, every ideogram on the coin looks off. Must be a replica.

Thank you.