You can absolutely paint electric baseboard heaters. Better yet, you can use standard paint without fear of any harsh smells wafting through your apartment. Even if there is some unpleasant odour the first time you turn it on, it should dwindle quickly as the paint settles onto the surface of the heater.
Before painting, sand off any rust that has accrued with time and coat the appliance with a thin layer of metal conditioner. Use anti-rust paint to prevent further spoilage of the materials.
As an alternative, consider latex-based paint. It’s more elastic than oil-based metal paint and more easily bears expansion and contraction from the heating/cooling cycle. But beware: lighter-coloured latex paints are prone to yellowing in warm conditions and thus may end up spoiling your desired look in a few seasons’ time.