A single-phase transformer has a magnetizing inductance of $\text{250 mH}$ and a core loss resistance of $300\: \Omega$, referred to primary side. When excited with a $\text{230 V}$, $\text{50 Hz}$ sinusoidal supply at the primary, the power factor of the input current drawn, with secondary on open circuit, is ______ (rounded off to two decimal places).