Number analysis
8
8 is a composite even number that factors as 2^3.
8 is a composite even number that factors as 2^3.
The number itself
- Value
- 8
- Digits
- 1
- Digit sum
- 8
- Reversed
- 8
- Palindrome
- Yes
8
Digit sum repeated until one digit remains; equals n mod 9 (with 9 for multiples of 9).
Reads the same in both directions.
Parity and primality
- Parity
- Even
- Prime
- No
- Squarefree
- No
- Prime power
- 2^3
- Powerful
- Yes
- Möbius μ(n)
- 0
- Nearest primes
- 7 ← → 11
Divisible by 2.
Composite — it factors as 2^3.
1 distinct prime factor, 3 with multiplicity.
At least one prime appears squared.
A single prime raised to a power.
Every prime factor appears at least squared.
Zero, because a squared prime divides n.
A gap of 4 between them.
Divisors
- Aliquot sum
- 7
- Classification
- Deficient
1, 2, 4, 8
The proper divisors — everything except n itself.
Its proper divisors fall short by 1.
How many integers from 1 to n share no factor with n.
Sums and additive structure
- Sum of two squares
- Yes
- Sum of three squares
- Yes
- Sum of four squares
- Yes
- Sum of two cubes
- 0³ + 2³
- Goldbach pair
- 3 + 5
2² + 2² = 8
Legendre's three-square theorem allows it.
Lagrange's four-square theorem: every non-negative integer is, without exception.
The smallest pair of primes summing to n. Goldbach’s conjecture says one always exists; it remains unproven.
Shapes and sequences
- Perfect cube
- Yes — 2³
- Fibonacci number
- Yes — index 6
- Power of two
- Yes — 2^3
Digit curiosities
- Happy number
- No
- Armstrong number
- Yes, trivially
- Harshad number
- Yes
- Collatz trajectory
- 3 steps to 1
Summing the squares of its digits falls into the 4 → 16 → 37 → … → 4 cycle.
Every single-digit number equals itself raised to the first power, so all ten qualify trivially.
Divisible by its digit sum 8 — 8 ÷ 8 = 1.
Peaks at 8 along the way.
Written other ways
- Binary
- 1000
- Octal
- 10
- Base 36
- 8
- Roman numerals
- VIII
- In words
- eight
- Scientific notation
- 8 × 10^0
Is 8 a prime number?
Composite — it factors as 2^3.
Nearby numbers
Other numeral systems
Beyond the bases and Roman numerals above, these notations write 8 their own way.
- Greek (alphabetic)
- Ηʹ
- Tamil
- ௮
References
Further reading: Wikipedia · MathWorld · Wikidata
Notations, naming and the links above come from Wikidata, whose structured data is dedicated to the public domain under CC0-1.0. Retrieved 2026-10-07.