Number reference
139 explained.
139: one hundred thirty-nine, prime; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- one hundred thirty-nine
- Classification
- prime
- Factors
- 1, 139
- Prime factorization
- 139
- Square root
- 11.789826
- Cube root
- 5.180101
- Binary
- 10001011
- Octal
- 213
- Hexadecimal
- 8B
- Roman numeral
- CXXXIX
- Digit sum
- 13
- Digital root
- 4
What makes 139 notable
- Prime. 139 is prime: it has exactly two divisors, 1 and itself, so it cannot be split into equal whole-number groups any other way.
139 in everyday use
One hundred thirty-nine is the upper half of the twin-prime pair 137 and 139, and it marks the start of a notable silence: the next prime after it is 149, so the ten consecutive numbers from 140 to 148 contain no prime at all. That is the first gap of exactly ten between consecutive primes. Gaps this size are routine among larger numbers, but below 140 the only wider gap is the fourteen-number stretch between 113 and 127.
The number is also the sum of five consecutive primes, 19 + 23 + 29 + 31 + 37, a coincidence that gives it a small place in recreational mathematics. It is a happy number: squaring its digits and adding gives 1 + 9 + 81 = 91, then 82, 68, 100, and finally 1. Being one more than 138, which is 2 × 3 × 23, it sits just after a number with three distinct prime factors, while having none but itself.
Nearby numbers
How to read this page
Because 139 is prime, the factor list stops at 1 and 139 itself, so it cannot be shared into equal whole-number groups. That is also what makes it useful as a building block: every larger number with 139 in its prime factorisation inherits it from here.
Percentage calculator · Fraction calculator · Browse Number Explorer