We present timing properties of the low-field magnetar CXOU J164710.2-455216 as measured with NICER, NuSTAR, Chandra and Neil-Gehrels-Swift observatories between 2017 and 2018 when the source was active. With the data, we were able to resolve the controversy on the source's surface magnetic-field strength (above or below 1014 G) and confirm that the source is indeed a low-field magnetar. The low dipole field, multiple (frequent) outbursts and the large characteristic age (1-2 Myr) suggest that the source may have strong multipole B components like some other magnetars do. We also find intriguing temporal behavior of the source. We attempt to interpret the observations using magnetar models.