The formula with 1.9 substituted
miles = 1.9 ÷ 1.609344 = 1.181
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, 1.9 km takes about 23 minutes. At an easy running pace of 10 km/h it takes about 11. In metres it is 1,900.
What 1.9 kilometres means in practice
At 1.9 km you are nearly at the 2 km mark and about 20 metres short of 1.2 miles. This is the distance of the swim in a half-distance triathlon, 1.9 km, which is 1.2 miles in the race literature.