Number analysis
188
188 is a composite even number that factors as 2^2 × 47.
188 is a composite even number that factors as 2^2 × 47.
The number itself
- Value
- 188
- Digits
- 3
- Digit sum
- 17
- Reversed
- 881
- Palindrome
- No
1 + 8 + 8
Digit sum repeated until one digit remains; equals n mod 9 (with 9 for multiples of 9).
Reverses to 881.
Parity and primality
- Parity
- Even
- Prime
- No
- Prime factorisation
- 2^2 × 47
- Squarefree
- No
- Möbius μ(n)
- 0
- Nearest primes
- 181 ← → 191
Divisible by 2.
Composite — it factors as 2^2 × 47.
2 distinct prime factors, 3 with multiplicity.
At least one prime appears squared.
Zero, because a squared prime divides n.
A gap of 10 between them.
Divisors
- Aliquot sum
- 148
- Classification
- Deficient
1, 2, 4, 47, 94, 188
The proper divisors — everything except n itself.
Its proper divisors fall short by 40.
How many integers from 1 to n share no factor with n.
Sums and additive structure
- Sum of two squares
- No
- Sum of three squares
- No
- Sum of four squares
- Yes
- Goldbach pair
- 7 + 181
A prime congruent to 3 mod 4 divides it an odd number of times, which rules it out.
Excluded by Legendre: it has the form 4^a(8b + 7).
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
- Figurate shapes
- None
Not triangular, square, pentagonal, hexagonal, cubic, Fibonacci, Lucas, Catalan, factorial or a power of two.
Digit curiosities
- Happy number
- Yes
- Harshad number
- No
- Collatz trajectory
- 106 steps to 1
Repeatedly summing the squares of its digits reaches 1.
Not divisible by its digit sum 17.
Peaks at 9,232 along the way.
Written other ways
- Binary
- 10111100
- Octal
- 274
- Hexadecimal
- BC
- Base 36
- 58
- Roman numerals
- CLXXXVIII
- In words
- one hundred and eighty-eight
- Scientific notation
- 1.88 × 10^2
Is 188 a prime number?
Composite — it factors as 2^2 × 47.
Nearby numbers
Other numeral systems
Beyond the bases and Roman numerals above, these notations write 188 their own way.
- Morse code
- · − − − − − − − · · − − − · ·
- Devanagari
- १८८
- Tamil
- ௱௮௰௮
- Thai
- ๑๘๘
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.