Number analysis
16
16 is a composite even number that factors as 2^4.
16 is a composite even number that factors as 2^4.
The number itself
- Value
- 16
- Digits
- 2
- Digit sum
- 7
- Reversed
- 61
- Palindrome
- No
1 + 6
Digit sum repeated until one digit remains; equals n mod 9 (with 9 for multiples of 9).
Reverses to 61.
Parity and primality
- Parity
- Even
- Prime
- No
- Squarefree
- No
- Prime power
- 2^4
- Powerful
- Yes
- Möbius μ(n)
- 0
- Nearest primes
- 13 ← → 17
Divisible by 2.
Composite — it factors as 2^4.
1 distinct prime factor, 4 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
- 15
- Classification
- Deficient
1, 2, 4, 8, 16
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
- 2³ + 2³
- Goldbach pair
- 3 + 13
0² + 4² = 16
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
- Square number
- Yes — the 4th
- Power of two
- Yes — 2^4
Digit curiosities
- Happy number
- No
- Harshad number
- No
- Collatz trajectory
- 4 steps to 1
Summing the squares of its digits falls into the 4 → 16 → 37 → … → 4 cycle.
Not divisible by its digit sum 7.
Peaks at 16 along the way.
Written other ways
- Binary
- 10000
- Octal
- 20
- Hexadecimal
- 10
- Base 36
- G
- Roman numerals
- XVI
- In words
- sixteen
- Scientific notation
- 1.6 × 10^1
Is 16 a prime number?
Composite — it factors as 2^4.
Nearby numbers
Other numeral systems
Beyond the bases and Roman numerals above, these notations write 16 their own way.
- Greek (alphabetic)
- ΙΣΤʹ
- Babylonian cuneiform
- 𒌋𒐚
- Tamil
- ௰௬
References
Further reading: Wikipedia · 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.