The formula with 1.7 substituted
miles = 1.7 ÷ 1.609344 = 1.056
The constant is an exact definition, not a rounded factor: the mile is 1.609344 km, the US gallon is 3.785411784 litres and the imperial gallon is 4.54609 litres. The Kilometres to Miles Converter explains where each comes from and gives a longer table.
At a walking pace of 5 km/h, 1.7 km takes about 20 minutes. At an easy running pace of 10 km/h it takes about 10. In metres it is 1,700.
What 1.7 kilometres means in practice
A 1.7 km walk is a little over a mile, and this value is looked up unusually often, probably because it is where the common one-mile walk lands once a detour or a loop back is added. Expect about 20 minutes on foot or 9 to 10 minutes jogging.