The article relates to decades-old problem of the mysterious coincidence of various Large numbers of magnitude ranging from 10⁴⁰ to 10¹²⁰ which sometimes appears in cosmology and quantum physics. Using well-known classical relations as well as the ideal Schwarzschild solution the exact relations of various large numbers, fine structure constant α and were found. The new Largest number law is claimed. The hypothetical approximations of the Hubble parameter—68.7457(82) km/s/Mpc, Hubble radius—14.2330(17) Gly, and some others were proposed. The exact formulae supporting P. Diracs Large number hypothesis and H. Weyls proposition were found. It is shown that all major physical constants with length dimension (from Compton wave length of universe through Planck and atomic scale up to Hubble sphere radius) could be derived from each other, and the table of the specific conversion rules has been developed. The model shows that Eddington-Weinberg relation can be transformed to precise identity. It is shown that both Bekenstein universal entropy bound and Hooft-Susskind holographic entropy bound are equal to the Largest number doubled.