All corrections of relative order ( 1 Z) (αZ)² to the hyperfine structure for the 2s ²S level of a lithiumlike multicharged ion are calculated. λ=0.3071 (3) cm is obtained for the wavelength of the transition between the hyperfine structure components for the 2s ²S level of ⁵⁷Fe²³⁺, which is important for astrophysics researches. A possibility for a verification of the quantum electrodynamics effects in the investigations of the hyperfine structure of the lithiumlike multicharged ions is noted.