21

 2 1  is a number that comprise s the sequence o f dig it s 2| 2  & 1| 1  of t he Arabic Numeral System  ; the most widely use d numeral system in the world. The number  2 1  first appeared on  SESAME STREET  i n 1 9 8 6  ( when  sponsor   number s  below 2| 2  & above  1 2  were first permitted ). In total, the number   2 1  has sponsored  episode s  , both of which first aired in the mid -  1 99 0 s. It remained the highest number  to sponsor an  episode  of  SESAME STREET  for several y ear s, until  producer s  chose the number  4 0  as a special feature in  episode 4 1 8 7  ( the  season 4 0  premiere ).

Skit s about 2 1

 * Number ella
 *  Ernie  ’ s "  1 2  &  2 1  " poem