• 67 can be written using four 4's:
67 is nontrivially palindromic in base 5 and base 6.
67 is an esthetic number in base 5, base 10 and base 16, because in such bases its adjacent digits differ by 1.
It is a strong prime.
67 is a truncatable prime.
It is a cyclic number.
It is a Chen prime.
It is a magnanimous number.
It is an alternating number because its digits alternate between even and odd.
67 is an undulating number in base 5 and base 6.
67 is a lucky number.
It is a plaindrome in base 7, base 10, base 12, base 14 and base 15.
It is a nialpdrome in base 3, base 9, base 11, base 13 and base 16.
It is a good prime.
67 is an equidigital number, since it uses as much as digits as its factorization.
67 is an odious number, because the sum of its binary digits is odd.
The square root of 67 is about 8.1853527719. The cubic root of 67 is about 4.0615481004.
Subtracting from 67 its product of digits (42), we obtain a square (25 = 52).