Seven

7 is an odd number.

7 is a prime number, which means it is only divisible by 1 and itself.

7 is a palindrome.

7 is a Harshad number, which means it is divisible by the sum of its digits (7 = 7, and 7 is divisible by 7).

In binary, 7 is represented as 111.

In hex, 7 is represented as 7.

7 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.

Prime factorization of 7: 7.