The limiting TODR is the longer of the all engines gross distance x 1.15 or the gross distance engine out. 1547 x 1.15 = 1779, longer than the engine out distance and therefore limiting. It is actually unlikely that a two engine aircraft would be all engines limited as loss of one engine = loss of half the thrust, a bad thing. Much more likely on a four engined aircraft where loss of an engine = loss of a quarter of the thrust.