49 (number)
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49 is a natural number that follows 48 and precedes 50. It is written in standard Hindu-Arabic numerals as 49, while in the Roman numeral system it is written as XLIX.
49 is a composite number, not a prime. It has three proper divisors: 1, 7, and 49. It is therefore the square of 7, making it one of the known square numbers.
Mathematical properties
49 = 7 × 7 = 7². Because it is the square of a prime number, it has only three divisors. The sum of its proper divisors (1 and 7) is 8, which is less than 49; therefore it is a deficient number. It is also a power, with base 7.
In other number systems, 49 is written as 110001 in binary, 61 in octal, and 31 in hexadecimal. The square root of 49 is 7, which is a whole number, meaning no fraction is required in the calculation.
General use
The number 49 appears in various counting systems: in historical years (such as 49 or 1949), in multiplication tables (7×7 being part of the seven times table), and in standard measurements. Like other numbers, its meaning depends on the context in which it is used.