The number 139 is an integer that follows 138 and precedes 140. It is an odd number and can be expressed as the sum of the first 10 prime numbers: 2 + 3 + 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 = 139. In mathematics, 139 is classified as a prime number, meaning it has no positive divisors other than 1 and itself. It is also notable in various fields, such as in the Periodic Table where the atomic number 139 corresponds to the element Promethium, a rare earth metal.