3 is an odd number.
3 is a prime number, which means it is only divisible by 1 and itself.
3 is a palindrome.
3 is a Sophie Germain prime, which means that 2 x 3 + 1 = 7 is also a prime number.
3 is a Harshad number, which means it is divisible by the sum of its digits (3 = 3, and 3 is divisible by 3).
In binary, 3 is represented as 11.
In hex, 3 is represented as 3.
3 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.
3 is the 4th Fibonacci number.
Prime factorization of 3: 3.