  A dormant Swift source J 164449.3+573451 (Sw 164449+57)recently experienced a
powerful outburst, caused most probably by a tidal disruption of a star by the
super-massive black hole at the center of the source. During the outburst, a
quasi periodic oscillation (QPO) was detected in the observed X-ray flux from
Sw 164449+57. We show that if the observed QPO belongs to a "3:2 twin peak QPO"
(with the second frequency not observed), the mass of the black hole in Sw
164449+57 is rather low, M ~ 10^5 M_sun, and the source belongs to a class of
intermediate mass black holes. The low mass of the source has been pointed out
previously by several authors.
