23:29 UTC - twenty-three twenty-nine UTC

Clock	Time	Spoken
24-hour clock	23:29	twenty-three twenty-nine, twenty-nine minutes past twenty-three, thirty-one minutes to midnight, thirty-one minutes to zero
12-hour clock	11:29 PM	eleven twenty-nine pm, twenty-nine minutes past eleven pm, thirty-one minutes to midnight, thirty-one minutes to twelve am
Military	2329Z	two-three-two-nine hours, twenty-three twenty-nine hours

AM or A.M. - latin ante meridiem, meaning before midday, PM or P.M. - latin post meridiem, meaning after midday. Letter 'Z' in military time indicates ZULU Time Zone which is equivalent to UTC.