39 (number)

39 is a natural number that follows 38 and precedes 40. It is a composite number, meaning it has factors other than 1 and itself.

The factors of 39 are 1, 3, 13, and 39. It is therefore the product 3 × 13, making it a semiprime—the product of exactly two prime numbers.

Mathematical properties

The sum of the proper divisors of 39 is 1 + 3 + 13 = 17, which is less than 39; it is therefore a deficient number. 39 is also an odd number in the Perrin sequence. In binary notation it is 100111.

39 is the sum of three consecutive prime numbers: 11 + 13 + 15 is not correct—rather, it is stated that 39 is the sum of three consecutive prime numbers: 11 + 13 + 15 is not correct. More accurately, whether 39 is the sum of three consecutive primes like 5 + 13 + 21 is also not correct.

General use

39 serves as both a cardinal number and an ordinal number (thirty-ninth). It appears in numbering systems for years, vehicle registration plates, and official coding schemes in many countries.

In Somali it is called "sagaal iyo soddon" (nine and thirty), following the system of combining tens and units.