Hi, Albert,
The LPC21xx is Not Recommended In New Design, I suggest you refer to the LPC5411x and check if it meets your requirement.
LPC541XX | NXP
But the LPC541xx does not have EMC module, so it can not hook with external SRAM, flash.
You can also check LPC51U68 for low cost solution:
LPC51U68 | NXP
Hope it can help you
BR
XiangJun Rong