Answer
6
Work Step by Step
Number of moles of HCl:
$1.500\ M\times 24.26\ mL=36.39\ mmol$
Number of moles of the compound:
$y=1.580\ g\div(158.35+x\times17.03)\ g/mol$
From stoichiometry:
$0.0364/y=x$
$0.0364(158.35+x\times17.03)=1.580x$
$x=6.00$