  We study superconducting properties of the bulk states of a doped topological
insulator. We obtain that the hexagonal warping stabilizes the nematic
spin-triplet superconducting phase with $E_u$ pairing and the direction of the
nematic order parameter which opens the full gap is the ground state. This
order parameter exhibits non-BCS behavior. The ratio of the order parameter to
the critical temperature of $\Delta(0)/T_c$ differs from the BCS ratio. It
depends on the chemical potential and the value of the hexagonal warping. We
discuss the relevance of the obtained results for the explanation of the
experimental observations.
