From the United 2018 Annual Report, which was put out on Feb 22nd, 2019.
Total 145s (XR, LR, ER)
Total Under CPA: 176
Owned by UAL: 82
Leased by UAL: 90
Owned or Leased by Regional Carrier: 4
Expressjet: 105
TransStates: 40
Commutair: 31
"In addition to the aircraft presented in the tables above, United owned the following aircraft listed below as of December 31, 2018: Three Embraer ERJ 145s, which are temporarily grounded."
"During the third quarter of 2018, United entered into an agreement with the lessor of 54 Embraer ERJ 145 aircraft to purchase those aircraft in 2019. The provisions of such agreement resulted in a change in accounting classification of the applicable leases from operating leases to capital leases up until the applicable purchase date"