Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
century [ˈsɛntjurɪ] n (period) век#; (CRICKET) сто очко́в
twentieth century двадца́тый век
in the twentieth century в двадца́том ве́ке
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.