9090909091

9090909091 is the ten-digit integer 9,090,909,091 in decimal notation. Its digit sequence largely alternates between 9 and 0 (9, 0, 9, 0, 9, 0, 9, 0, 9) and ends with 1, giving a simple, recognizable pattern of repeating 90 blocks followed by a final 1.

Numerical properties of the number include that it is odd, so it is not divisible by 2 or any even number, and its last digit rules out divisibility by 5. The sum of its digits is 46, which means the number is not divisible by 3 or 9 (digital root is 1). A divisibility test for 11 shows that 9090909091 is divisible by 11, with a quotient of 826,446,281, since 11 × 826,446,281 = 9,090,909,091.

In terms of factorization, the number can be expressed as 9090909091 = 11 × 826,446,281. This illustrates how a simple digit pattern does not preclude a number from being composite, and it provides a concrete example of the divisibility-by-11 rule in action. The value lies in the range accessible to 64-bit integer arithmetic and serves as a compact test case for algorithms dealing with large integers, pattern recognition, and divisibility properties.

Contextual notes: the repeating 09 pattern in the digit sequence echoes the well-known repeating decimal 0.090909… which equals 1/11, underscoring a connection between digit patterns and basic fraction representations.