1 Kg = 1,000g
Therefore 1.33 × 10^-7 g = 1.33 × 10^-10 kg
1m³ = 1,000,000cm³
Therefore 1 cm³ = 1 × 10^-6 m³
Dividing the mass per unit volume you get:
(1.33 × 10^-10 kg) ÷ (1 × 10^-6 m³)
= 1.33 × 10^(-10--6) = 1.33 × 10^(-10 + 6) = 1.33 × 10^-4 kg/m³
Density = 1.33 × 10^-4 kg/m³