88888...00001 (1350-digits)

This number is a probable-prime (likely to be a prime but we have not (re-)proven it on this site).

The "Trinity Hall Prime", a titanic prime number whose digits can be arranged into a rectangle containing an image of the coat of arms of Trinity Hall, the oldest college of Cambridge University:

  888888888888888888888888888888
  888888888888888888888888888888
  888888888888888888888888888888
  888111111111111111111111111888
  888111111111111111111111111888
  888111111811111111118111111888
  888111118811111111118811111888
  888111188811111111118881111888
  888111188811111111118881111888
  888111888811111111118888111888
  888111888881111111188888111888
  888111888888111111888888111888
  888111888888888888888888111888
  888111888888888888888888111888
  888111888888888888888888111888
  888811188888888888888881118888
  188811188888888888888881118881
  188881118888888888888811188881
  118888111888888888888111888811
  111888811118888888811118888111
  111188881111111111111188881111
  111118888111111111111888811111
  111111888811111111118888111111
  111111188881111111188881111111
  111111118888811118888811111111
  111111111888881188888111111111
  111111111118888888811111111111
  111111111111888888111111111111
  111111111111118811111111111111
  111111111111111111111111111111
  062100000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000000
  000000000000000000000000000001.

Trinity Hall was founded in the year 1350 by William Bateman, the Bishop of Norwich, and this prime has 1350 digits. Found by James McKee, it was left as a parting gift to the college in 1994.