10101

10101 is a five-digit sequence that can denote numbers in different numeral systems. It is most commonly encountered as a binary numeral, a decimal integer, or its hexadecimal equivalent.

In binary notation, 10101_2 equals 21 in decimal. The sequence is a binary palindrome.

In decimal notation, 10101 denotes the integer ten thousand one hundred one (10,101). In hexadecimal, the same value is 0x2775.

Factorization and arithmetic: As a decimal number, 10101 = 3 × 7 × 13 × 37. It is a divisor of 999,999 because 10^6 − 1 = (10^2 − 1)(10^4 + 10^2 + 1) = 99 × 10101.

Notes: The binary form 10101_2 is a palindrome; the decimal form 10101 has a pattern that yields a notable factorization. The string is often used in teaching examples of base conversion and number factorization, illustrating how the same digit sequence can represent different values depending on the numeral system.