Duplicate entry for key. even though it is not Above image describes my tables 'Details'

And above is my entire table only one row. and  i have tried 'INSERT' to table

INSERT INTO `details`( 
  `Name`, 
  `dob`, 
  `age`, 
  `qualification`, 
  `ExpYr`, 
  `ExpMnth`, 
  `Email`, 
  `Contact`, 
  `resume`)
VALUES (
  'viviek',
  '0899-06-21',
  '1117',
  'hihh',
  '2',
  '3',
  '1026viivek@gmail.com',
  '9645904409',
  'Array')


but it showing an error like


  Duplicate entry '2147483647' for key 'Contact'


Why is it showing error with different value than key value in table for contact?
This is because the maximum possible stored value for the int(11) (32-bit signed integer) Contact column is 2147483647.

MySQL is silently ignoring the fact that the value 9645904409 is larger than this &amp; is "truncating" it down to 2147483647. Multiple values truncated to 2147483647 are causing the unique constraint violation.

If Contact is supposed to be a phone number, I suggest changing the datatype to VARCHAR(20) or similar.