37

37 is a natural number that comes after 36 and before 38. In mathematics, it is prime, the 12th prime number. It is also a centered hexagonal number, equal to 3n(n−1)+1 with n = 4. A notable consequence is that 37 × 3 = 111, so multiples of 37 with multipliers that are multiples of 3 yield repdigits, such as 111, 222, 333, and so on.

In other representations, 37 is XXXVII in Roman numerals. In binary it is 100101, and in hexadecimal it is 25. In ASCII, the decimal value 37 corresponds to the percent sign (%).

In science, 37 is the atomic number of rubidium (Rb), an alkali metal. Rubidium is a soft, highly reactive element that occurs naturally in minerals such as lepidolite and in small amounts in various salts and brines. It is used in research and in practical devices, including rubidium-vapor atomic clocks and certain magnetometers.

Geographically, the 37th parallel north is a circle of latitude at roughly 37 degrees north. It crosses parts of North America, Europe and Asia and is sometimes referenced in historical and regional contexts.

Overall, 37 appears across mathematics, science and geography as a number with several distinct and well-documented properties, while also appearing in everyday numeric systems and measurements.