The 15 digits are all numbers the VIN is always 17 and includes letters. It might be a frame number. I don't think it's been registered although it's not new. I'd guess about 5 years but there's no odometer so I'm can't estimate mileage.
That's sort of the point I've stripped all the panels off and can't find any sign of it ever having a VIN. There seams to be a 15 digit number on the frame, which makes me think it might be classed as a bike?