123
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 6
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 168
- Proper Divisor Sum (Aliquot Sum)
- 45
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 80
- Möbius Function
- 1
- Radical
- 123
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- yes
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 46
- Smith Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- Squarefree Number
- yes
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Names
- German
- einshundertdreiundzwanzig· ordinal: einshundertdreiundzwanzigste
- English
- one hundred twenty-three· ordinal: one hundred twenty-third
- Spanish
- ciento veintitrés· ordinal: 123º
- French
- cent vingt-trois· ordinal: cent vingt-troisième
- Italian
- centoventitre· ordinal: 123º
- Latin
- centum viginti tres· ordinal: 123.
- Portuguese
- cento e vinte e três· ordinal: 123º
Appears in sequences
- Lucas numbers (beginning with 1): L(n) = L(n-1) + L(n-2) with L(1) = 1, L(2) = 3.at n=9A000204
- Numbers where total number of 1-bits in the exponents of their prime factorization is even; a 2-way classification of integers: complement of A000028.at n=64A000379
- Numbers that are the sum of 3 but no fewer nonzero squares.at n=51A000419
- n written in base where place values are positive cubes.at n=46A000433
- 1 together with products of 2 or more distinct primes.at n=46A000469
- Number of nonnegative solutions of x^2 + y^2 = z in first n shells.at n=58A000592
- Expansion of 1/((1-x)^2*(1-x^2)*(1-x^3)).at n=13A000601
- Number of nonnegative solutions to x^2 + y^2 <= n^2.at n=12A000603
- Number of points of norm <= n in cubic lattice.at n=3A000605
- a(n) is the number of conjugacy classes in the alternating group A_n.at n=15A000702
- Total number of 1's in binary expansions of 0, ..., n.at n=46A000788
- Numbers beginning with a vowel in English.at n=37A000852
- Numbers ending with a vowel in American English.at n=55A000861
- Numbers beginning with letter 'o' in English.at n=24A000865
- a(2n) = n+2, a(2n-1) = smallest number requiring n+2 letters in English.at n=42A000916
- Dimension of the n-th graded piece of the mod-2 Steenrod algebra A_2.at n=47A000929
- n! never ends in this many 0's.at n=23A000966
- Sum of proper divisors (or aliquot parts) of n: sum of divisors of n that are less than n.at n=71A001065
- Smallest natural number requiring n letters in English.at n=21A001166
- Zarankiewicz's problem k_2(n).at n=22A001197