  The analysis of distributions of some parameters of radio pulsars emitting
X-ray radiation was carried out. The majority of such pulsars has short spin
periods with the average value $< P >$ = 133 msec. The distribution of period
derivatives reveals a bimodality, dividing millisecond ($< log \dfrac{dP}{dt}>$
= -19.69) and normal ($< log \dfrac{dP}{dt}> $ = -13.29) pulsars. Magnetic
fields at the surface of the neutron star are characterized by the bimodal
distribution as well. The mean values of $<log B_s>$ are $8.48$ and $12.41$ for
millisecond pulsars and normal ones, respectively. The distribution of magnetic
fields near the light cylinder, it does not show the noticeable bimodality. The
median value of $log B_{lc}$ = 4.43 is almost three orders higher comparing
with this quantity ($<log B_{lc}>$ = 1.75) for radio pulsars without registered
X-ray emission. Losses of rotational energy ($<log \dfrac{dE}{dt}>$ = 35.24)
are also three orders higher than corresponding values for normal pulsars.
There is the strong correlation between X-ray luminosities and losses of
rotational energies. The dependence of the X-ray luminosity on the magnetic
field at the light cylinder has been detected. It shows that the generation of
the non-thermal X-ray emission takes place at the periphery of the
magnetosphere and is caused by the synchrotron mechanism. We detected the
positive correlations between luminosities in radio, X-ray and gamma -ray
ranges. Such correlations give the possibility to carry out a purposeful search
for pulsars in one of these ranges if they radiate in other one.
