How to add SerialNumber as Subject alternative Name in Bouncy Castle

Question

I am trying to add SerialNumber and UID as SAN but don't know how to add it, I am trying this code but it gives me error:

 GeneralName name1 = new GeneralName(GeneralName.DnsName, "bc1.local");
 GeneralName name2 = new GeneralName(X509Name.SerialNumber, "1234567890");
 GeneralName name3 = new GeneralName(X509Name.UID, "123456789123456");

 certGen.AddExtension(X509Extensions.SubjectAlternativeName, false,  name1,name2,name3);

the error I got it Argument 'number' cannot convert from string to int and I want it to be as string to add it in CSR.