Sandisk Ultra Flair USB 3.0 Flash Drive 64 GB.

check the drive itself. the marking should indicate the capacity. check to make sure it was not some sort of packaging mistake. 

if the drive itself shows 64GB then you can try using the format tool in the link below. it may be able to recover the full capacity

https://kb.sandisk.com/app/answers/detail/a_id/19258/