|  |  | Abstract: |  Let  be a positive integer with  , and let  denote the unitary analogue of Euler's totient function  . Using Grytczuk-Wójtowicz's techniques from the paper [2] we strengthen considerably the lower estimations of the solutions  of the equation  . Moreover, we show that the set of positive integers, which do not fulfil this equation for any  , contains an interesting subset generated by Ramsey's theorem. |