Number reference
149 explained.
149: one hundred forty-nine, prime; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- one hundred forty-nine
- Classification
- prime
- Factors
- 1, 149
- Prime factorization
- 149
- Square root
- 12.206556
- Cube root
- 5.301459
- Binary
- 10010101
- Octal
- 225
- Hexadecimal
- 95
- Roman numeral
- CXLIX
- Digit sum
- 14
- Digital root
- 5
What makes 149 notable
- Prime. 149 is prime: it has exactly two divisors, 1 and itself, so it cannot be split into equal whole-number groups any other way.
149 in everyday use
One hundred forty-nine appears in astronomy as the leading digits of the astronomical unit: the average distance from Earth to the Sun is about 149.6 million kilometres, and the value is fixed by definition at exactly 149,597,870.7 km. Every planetary distance quoted in astronomical units is measured against that yardstick. Light covers the distance in a little over eight minutes, so the sunlight arriving now left the Sun roughly 149.6 million kilometres and eight minutes ago.
The number itself is prime and forms twin primes with 151, following the prime-free stretch from 140 to 148. It is an emirp: reversing its digits gives 941, which is also prime. It can be written as the sum of two squares, 10² + 7², and it is a Tribonacci number, appearing in the sequence where each term is the sum of the previous three: 1, 1, 2, 4, 7, 13, 24, 44, 81, 149.
Nearby numbers
How to read this page
Because 149 is prime, the factor list stops at 1 and 149 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 149 in its prime factorisation inherits it from here.
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