Unfortunately no, as the CPU is soldered to the motherboard. You would have to replace the entire motherboard if one exists with a CPU that has better performance than yours. And considering the age of your system it may be wiser to consider replacing it with a much newer more powerful system.
Bom dia Dell.  Possuo um Inspiron 5421 i5 4gb e gostaria de saber si consigo atualizar o processador dele para um melhor ??
Upgrade