151
E151 is Brilliant Black BN.
- Odd
- Prime
Where 151 fits
Why 151 is special
It is one of the colours restricted or avoided in several jurisdictions, and it is banned outright in some, which is why product formulations differ by market.
151 is part of
Factors & digit properties
- Divisors (2)
- 1, 151
- Prime factorisation
- 151
- Digit sum
- 7
- Digital root
- 7
Representations
- Decimal
- 151
- Binary
- 10010111
- Octal
- 227
- Hexadecimal
- 97
- Roman numeral
- CLI
- Scientific notation
- 1.510 × 10^2
Other mathematical patterns
- Palindromic number
- Deficient number
- Lucky number (mathematical sieve)
- Twin prime
Related numbers & connections
Both are synthetic dyes subject to differing national restrictions, which is why formulations vary by market.
View 132 →Everyday life
E151 Brilliant Black BN is a synthetic azo dye permitted in the European Union and prohibited in several other jurisdictions, producing market-specific formulations.
DocumentedEveryday lifeGeography: European Union and states adopting the E number systemPeriod: 1962–
Common questions
Is 151 a prime number?
Yes, 151 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 151?
The factors of 151 are 1, 151.
What is 151 in Roman numerals?
151 in Roman numerals is CLI.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 3 August 2026