1
1 is the multiplicative identity. By modern mathematical convention it is classified as neither prime nor composite.
Where 1 fits
Why 1 is special
1 is the building block of every other whole number, yet is deliberately excluded from the primes.
1 in Numbers Around Us
1 is part of
Factors & digit properties
- Divisors (1)
- 1
- Digit sum
- 1
- Digital root
- 1
Representations
- Decimal
- 1
- Binary
- 1
- Octal
- 1
- Hexadecimal
- 1
- Roman numeral
- I
- Scientific notation
- 1.000 × 10^0
Other mathematical patterns
- Triangular number
- Palindromic number
- Deficient number
- Happy number
- Highly composite number
- Narcissistic (Armstrong) number
- Automorphic number
- Pentagonal number
- Hexagonal number
- Harshad (Niven) number
- Lucky number (mathematical sieve)
Related numbers & connections
0 and 1 are the additive and multiplicative identities respectively — the two foundational values every other number is built from under addition and multiplication.
View 0 →1 is the atomic number of hydrogen.
1 is one of the two digits (with 0) used to represent all data in the binary number system.
Shares a distinctive class
- is associated with0
why?
Strength 0.50, confidence "high".
Scientific association
- has scientific association withHydrogen (chemical element)
why?
Strength 0.50, confidence "high".
Numbers Around Us
- appears inBinary number system
why?
Strength 0.50, confidence "high".
Science
1 is the atomic number of hydrogen, the lightest and most abundant chemical element in the universe.
DocumentedScience1 is the atomic number of hydrogen, the lightest and most abundant chemical element in the universe.
DocumentedScience
Common questions
Is 1 a prime number?
No, 1 is not prime.
What are the factors of 1?
The factors of 1 are 1.
What is 1 in Roman numerals?
1 in Roman numerals is I.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 2 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026