21111111111

21111111111 is a unique and intriguing number that has garnered attention due to its mathematical properties and cultural significance. The number is composed entirely of the digit '1', making it a repdigit. In base 10, it is written as 21,111,111,111, and it is the largest repdigit number with 11 digits. The number 21111111111 is also notable for its divisibility properties. It is divisible by 11, as the alternating sum of its digits (2 - 1 + 1 - 1 + 1 - 1 + 1 - 1 + 1 - 1 + 1) equals zero, which is a multiple of 11. Additionally, it is divisible by 3, as the sum of its digits (2 + 9*1) is 11, which is a multiple of 3. This makes 21111111111 a sphenic number, as it is the product of three distinct prime factors: 2, 3, and 11. The number has also appeared in various forms of media, including literature and film, often symbolizing infinity, repetition, or the passage of time. Its simplicity and mathematical properties make it a subject of interest for mathematicians, number theorists, and enthusiasts alike.