(?:5[1-5][0-9]{2}|222[1-9]|22[3-9][0-9]|2[3-6][0-9]{2}|27[01][0-9]|2720)[ \-,]?[0-9]{4}[ \-,]?[0-9]{4}[ \-,]?[0-9]{4}
#+ number only field starts with 51-55 OR 2221-2720
2221006091057667
5283783695553246
#+DINERS CLUB - MASTER CARD NORTH AMERICA
5582946852021517
#+ number string
<sometag1>somedata</sometag1><sometag2><num>2221006091057667</num>
<sometag1>somedata</sometag1><sometag2><num>5283783695553246</num>
<sometag1>somedata</sometag1><sometag2><num>5582946852021517</num>
#+ with spaces
<sometag1>somedata</sometag1><sometag2><num> 2221 0060 9105 7667</num>
<sometag1>somedata</sometag1><sometag2><num> 5283 7836 9555 3246</num>
<sometag1>somedata</sometag1><sometag2><num> 5582 9468 5202 1517</num>
#+ with dash
<sometag1>somedata</sometag1><sometag2><num>2221-0060-9105-7667</num>
<sometag1>somedata</sometag1><sometag2><num>5283-7836-9555-3246</num>
<sometag1>somedata</sometag1><sometag2><num>5582-9468-5202-1517</num>
#+ with comma
<sometag1>somedata</sometag1><sometag2><num>2221,0060,9105,7667</num>
<sometag1>somedata</sometag1><sometag2><num>5283,7836,9555,3246</num>
<sometag1>somedata</sometag1><sometag2><num>5582,9468,5202,1517</num>
#+ bigger numbers
<sometag1>somedata</sometag1><sometag2><num>344722210060910576676566</num>
<sometag1>somedata</sometag1><sometag2><num>3528378369555324645566</num>
<sometag1>somedata</sometag1><sometag2><num>3455655829468520215176</num>
#+ bigger numbers with space
<sometag1>somedata</sometag1><sometag2><num>3442221 0060 9105 76673565 566</num>
<sometag1>somedata</sometag1><sometag2><num>3449 95283 7836 9555 324665 566</num>
<sometag1>somedata</sometag1><sometag2><num>344 5582 9468 5202 151765 566</num>
#- SHOULD NOT MATCH with other starting numbers
32042877059846
37592951984335
39152870324798
<sometag1>somedata</sometag1><sometag2><num>5682 9468 5202 1517 566</num>
