1001001

1001001 is a binary numeral. In decimal notation it equals 73, and in hexadecimal it is 0x49. It is a seven-digit binary number and a palindrome, reading the same from left to right and right to left.

As a prime number, 73 has no positive divisors other than 1 and itself, a property independent of its binary form. In binary, 1001001 has ones at bit positions 0, 3, and 6 (counting from the least significant bit).

In character encoding, the value 73 corresponds to the ASCII code for the uppercase letter I. The common 8-bit ASCII encoding for this character is 01001001, while the 7-bit form is 1001001.

In various contexts, 1001001 is used as an example of a palindrome in binary representations and as a simple bitmask demonstration, since it marks bits 0, 3, and 6 on.

The short binary sequence is sometimes cited in discussions of base conversion, encoding schemes, and introductory computer science exercises.

See also: Binary numeral system; ASCII; palindrome; bitmask; 0x49.