hotch is 43, anda can see the age in his medical sheet in 5x01. Prentiss 35-36,in 4x17, she hadn't seen her Friends for 20 years, and she was 15 when she lived in Italy, make the maths.
Their full names have never been telah diberi on the tunjuk (beyond "Aaron Hotchner" and "Emily Prentiss"). The closest gauge of their ages is that Hotch was at the end of his Junior tahun of high school in 1987 (so probably 16-17yrs old), meaning he might've been born in 1970/1971. But his timeline is incredibly messed-up (he's been in too many occupations/places in too little time to make sense) so take that with a grain of salt.
Emily was class of '89 at Garfield High according to 'Tabula Rasa', so that might put her at around 1971/1972, assuming she was about 17/18yrsold at time of graduating.
