The comparative analysis of parameters is carried out for two samples of radio pulsars .
Objects of the first sample have periods P > 2 sec , the second is characterized by magnetic fields at the neutron star surface Bs > 4.4 \times 10 ^ { 13 } G. The main goal of this analysis is to find some differences between normal pulsars and anomalous X-ray pulsars ( AXP ) and soft gamma-ray repeaters ( SGR ) with the similar values of periods and magnetic fields .
It is shown that the dependence of period derivatives on periods for pulsars with long periods is dP / dt \propto P ^ { 1.67 } .
This means that we must search for another braking mechanism differing from the magnetic dipole one which gives dP / dt \propto P ^ { -1 } or use some specific distributions of parameters .
On the other hand , radio pulsars with strong magnetic fields and AXP/SGR can be described by the magnetic dipole model .
Radio pulsars with P > 2 sec have ages on average two orders of magnitude higher than objects with Bs > 4.4 \times 10 ^ { 13 } G and are located much higher above the Galactic plane .
The obtained results show that the main feature of AXP/SGR is the strong magnetic field and not the large period .