• 47 can be written using four 4's:
47 is an esthetic number in base 7, base 11 and base 15, because in such bases its adjacent digits differ by 1.
It is a weak prime.
47 is a truncatable prime.
It is a cyclic number.
It is a Chen prime.
47 is a repfigit number.
It is a Lucas number.
It is a magnanimous number.
It is an Ulam number.
It is an alternating number because its digits alternate between even and odd.
It is a Carol number, being equal to (23 - 1)2 - 2.
It is a plaindrome in base 4, base 6, base 8, base 10, base 12, base 13, base 14 and base 16.
It is a nialpdrome in base 7, base 9, base 11 and base 15.
It is a congruent number.
47 is an equidigital number, since it uses as much as digits as its factorization.
47 is an odious number, because the sum of its binary digits is odd.
The square root of 47 is about 6.8556546004. The cubic root of 47 is about 3.6088260801.
Subtracting from 47 its sum of digits (11), we obtain a triangular number (36 = T8).
Adding to 47 its reverse (74), we get a palindrome (121).
Subtracting 47 from its reverse (74), we obtain a cube (27 = 33).