180
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 18
- Divisor Sum
- 546
- Proper Divisor Sum (Aliquot Sum)
- 366
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 48
- Möbius Function
- 0
- Radical
- 30
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 3
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
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 18
- Smith Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Carmichael Number
- no
Classification
- Even
- yes
- Odd
- no
Names
- German
- einshundertachtzig· ordinal: einshundertachtzigste
- English
- one hundred eighty· ordinal: one hundred eightieth
- Spanish
- ciento ochenta· ordinal: 180º
- French
- cent quatre-vingts· ordinal: cent quatre-vingtsième
- Italian
- centoottanta· ordinal: 180º
- Latin
- centum octoginta· ordinal: 180.
- Portuguese
- cento e oitenta· ordinal: 180º
Appears in sequences
- Number of ways of making change for n cents using coins of 1, 2, 5, 10 cents.at n=39A000008
- Definition (1): Number of n-bead binary necklaces with beads of 2 colors where the colors may be swapped but turning over is not allowed.at n=12A000013
- Number of positive integers <= 2^n of form x^2 + y^2.at n=9A000050
- Numbers k such that k^4 + 1 is prime.at n=27A000068
- a(n) = n^2*Product_{p|n} (1 + 1/p).at n=9A000082
- Number of series-parallel networks with n unlabeled edges. Also called yoke-chains by Cayley and MacMahon.at n=6A000084
- Number of cusps of principal congruence subgroup Gamma^{hat}(n).at n=17A000114
- Number of cusps of principal congruence subgroup Gamma^{hat}(n).at n=20A000114
- Denumerants: Expansion of 1/((1-x)*(1-x^2)*(1-x^5)).at n=56A000115
- Number of even sequences with period 2n (bisection of A000013).at n=6A000116
- Number of ways of writing n as a sum of 10 squares.at n=2A000144
- Number of n-node rooted trees of height 5.at n=9A000342
- Number of permutations of an n-sequence discordant with three given permutations (see reference) in n-2 places.at n=2A000388
- Numbers that are the sum of 2 but no fewer nonzero squares.at n=58A000415
- Number of permutations of an n-sequence discordant with three given permutations (see reference) in n-4 places.at n=2A000440
- a(n) = (2n)!(2n+1)!/n!^4, or equally (2n+1)*binomial(2n,n)^2.at n=2A000515
- Expansion of Product_{k >= 1} (1 - x^k)^6.at n=21A000729
- Number of compositions of n into 3 ordered relatively prime parts.at n=23A000741
- Boustrophedon transform of squares.at n=4A000745
- Dimension of the n-th graded piece of the mod-2 Steenrod algebra A_2.at n=54A000929