Thirty Three (33)

33 = 3*11 = 2^5 +1 

33 = XXXIII in Roman Numerals 

33 = 21 in Hexadecimal = 41 in Octal = 100001 in Binary

The highest currently recognized degree in Freemasonry is now the 33rd degree. 

Jesus Christ is said to have died at age 33 and is said to have done 33 miracles.

The age of all people in Heaven is considered to be 33 by some religions.  (I read this somewhere but do I not remember which religion or religions it applied to.)

The temperature of boiling water is 33 degrees on the Newton Temperature Scale.

The sum of the first 4 factorials is 33. (1!=1, 2!=2, 3!=6, 4!=24 and 1 + 2 + 6 + 24 = 33)

The atomic number of arsenic is 33.

The human spine has 33 vertebrae.

Harry S. Truman was the 33rd POTUS and was also a 33rd Degree Mason.