The rupee pared initial gains and settled 21 paise lower at 81.59 (provisional) against the US dollar on Monday, tracking a rebound in the greenback overseas and a muted trend in domestic equities.Forex traders said risk aversion in international markets and sustained foreign fund outflows weighed on investor sentiments.At the interbank foreign exchange market, the rupee opened on a positive note at 81.29 against the greenback, but pared the gains and fell to an intra-day low of 81.73.The domestic currency finally settled at 81.59, down 21 paise over its previous close.