MySQL Replication Duplicate Entry for Primary Key

160523 13:07:29 [ERROR] Slave SQL: Error 'Duplicate entry '914166' for key
'PRIMARY'' on query. Default database: 'zo_dev_20121216'. Query: 'UPDATE    
   activity
SET
   activity_type_id = 9,
   subject = 'Send departure email',
   date_due = '2016-05-26 01:00',
   date_start = '2016-05-23 01:00',
   activity_status_id = 1,
   content = 'Send departure email'
WHERE
   id = 2888555', Error_code: 1062
160523 13:07:29 [Warning] Slave: Duplicate entry '914166' for key 'PRIMARY'     
Error_code: 1062
160523 13:07:29 [ERROR] Error running query, slave SQL thread aborted. Fix     
the problem, and restart the slave SQL thread with "SLAVE START". We stopped   
at log 'mysql-bin.000004' position 14847360

Many people have suggested to use slave-skip-error option etc.. but that will completely avoid the query. How do you actually continue with the query that poses the error ? Also, I could not find a good answer as to why this actully occurs and what the number "914166" indicates ? Can someone please explain ?