5 is an odd number.
5 is a prime number, which means it is only divisible by 1 and itself.
5 is a palindrome.
5 is a Sophie Germain prime, which means that 2 x 5 + 1 = 11 is also a prime number.
5 is a Harshad number, which means it is divisible by the sum of its digits (5 = 5, and 5 is divisible by 5).
In binary, 5 is represented as 101.
In hex, 5 is represented as 5.
5 is an Armstrong (or Narcissistic) number, which means it is the sum of its own digits each raised to the power of the number of digits.
5 is the 5th Fibonacci number.
Prime factorization of 5: 5.