By accounting for realistic interparticle interaction energy of fine dry nanoparticles, an off-lattice Monte Carlo (MC) simulation approach is used to gain insight into such properties of agglomerates of nanoparticles with primary sizes ranging from 10 nm to 100 nm. This novel numerical approach allows for assessment of the mechanical properties and morphological features of the agglomerates. An interesting outcome is that the fractal dimension depends on the material properties represented via interaction energy. The agglomerate porosity increases with increasing agglomerate mass and may approach unity. With increasing Hamaker constant and fixed particle size, the agglomerates are characterized by a lower fractal dimension, higher packing porosity, higher mechanical strength, larger agglomeration size, and lower crystalline fraction. For a fixed Hamaker constant, agglomerates of the smaller primary particles exhibit a more compact packing structure, higher mechanical strength, smaller agglomerate size, and higher crystalline fraction. The local structure analysis indicates that for a fixed Hamaker constant, there are more particles in crystalline structure within the agglomerates constituted by the smaller primary particles. Likewise, for a fixed primary particle size, a lower Hamaker constant allows particles to configure into more stable agglomerate structures, thus providing useful insights into agglomerate morphology.