Number analysis
10
10 is a composite even number that factors as 2 × 5.
10 is a composite even number that factors as 2 × 5.
The number itself
- Value
- 10
- Digits
- 2
- Digit sum
- 1
- Reversed
- 1
- Palindrome
- No
1 + 0
Digit sum repeated until one digit remains; equals n mod 9 (with 9 for multiples of 9).
Reverses to 1.
Parity and primality
- Parity
- Even
- Prime
- No
- Prime factorisation
- 2 × 5
- Squarefree
- Yes
- Semiprime
- Yes
- Möbius μ(n)
- 1
- Nearest primes
- 7 ← → 11
Divisible by 2.
Composite — it factors as 2 × 5.
2 distinct prime factors, 2 with multiplicity.
No prime divides it twice.
A product of exactly two primes, counted with multiplicity.
(−1) to the power of 2 distinct prime factors.
A gap of 4 between them.
Divisors
- Aliquot sum
- 8
- Classification
- Deficient
1, 2, 5, 10
The proper divisors — everything except n itself.
Its proper divisors fall short by 2.
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
- Goldbach pair
- 3 + 7
1² + 3² = 10
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
- Triangular number
- Yes — the 4th
Digit curiosities
- Happy number
- Yes
- Harshad number
- Yes
- Collatz trajectory
- 6 steps to 1
Repeatedly summing the squares of its digits reaches 1.
Divisible by its digit sum 1 — 10 ÷ 1 = 10.
Peaks at 16 along the way.
Written other ways
- Binary
- 1010
- Octal
- 12
- Base 36
- A
- In words
- ten
- Scientific notation
- 1.0 × 10^1
Is 10 a prime number?
Composite — it factors as 2 × 5.
Nearby numbers
Other numeral systems
Beyond the bases and Roman numerals above, these notations write 10 their own way.
- Greek (alphabetic)
- Ιʹ
- Tamil
- ௰
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.