  CoRoT-2 is one of the most unusual planetary systems known to date. Its host
star is exceptionally active, showing a pronounced, regular pattern of optical
variability caused by magnetic activity. The transiting hot Jupiter, CoRoT-2b,
shows one of the largest known radius anomalies. We analyze the properties and
activity of CoRoT-2A in the optical and X-ray regime by means of a high-quality
UVES spectrum and a 15 ks Chandra exposure both obtained during planetary
transits. The UVES data are analyzed using various complementary methods of
high-resolution stellar spectroscopy. We characterize the photosphere of the
host star by deriving accurate stellar parameters such as effective
temperature, surface gravity, and abundances. Signatures of stellar activity,
Li abundance, and interstellar absorption are investigated to provide
constraints on the age and distance of CoRoT-2. Furthermore, our UVES data
confirm the presence of a late-type stellar companion to CoRoT-2A that is
gravitationally bound to the system. The Chandra data provide a clear detection
of coronal X-ray emission from CoRoT-2A, for which we obtain an X-ray
luminosity of 1.9e29 erg/s. The potential stellar companion remains undetected
in X-rays. Our results indicate that the distance to the CoRoT-2 system is
approximately 270 pc, and the most likely age lies between 100 and 300 Ma. Our
X-ray observations show that the planet is immersed in an intense field of
high-energy radiation. Surprisingly, CoRoT-2A's likely coeval stellar
companion, which we find to be of late-K spectral type, remains X-ray dark.
Yet, as a potential third body in the system, the companion could account for
CoRoT-2b's slightly eccentric orbit.
