155
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 192
- Proper Divisor Sum (Aliquot Sum)
- 37
- 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
- 120
- Möbius Function
- 1
- Radical
- 155
- 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
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 85
- 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
- einshundertfünfundfünfzig· ordinal: einshundertfünfundfünfzigste
- English
- one hundred fifty-five· ordinal: one hundred fifty-fifth
- Spanish
- ciento cincuenta y cinco· ordinal: 155º
- French
- cent cinquante-cinq· ordinal: cent cinquante-cinqième
- Italian
- centocinquantacinque· ordinal: 155º
- Latin
- centum quinquaginta quinque· ordinal: 155.
- Portuguese
- cento e cinquenta e cinco· ordinal: 155º
Appears in sequences
- Number of primitive permutation groups of degree n.at n=80A000019
- Local stops on New York City A line subway.at n=17A000054
- Let A(n) = #{(i,j,k): i^2 + j^2 + k^2 <= n}, V(n) = (4/3)Pi*n^(3/2), P(n) = A(n) - V(n); sequence gives values of n where |P(n)| sets a new record.at n=11A000092
- 3*n - 2*floor(sqrt(4*n+5)) + 5.at n=60A000277
- 1 together with products of 2 or more distinct primes.at n=58A000469
- Number of permutations of length n by rises.at n=2A000544
- n! never ends in this many 0's.at n=30A000966
- Expansion of g.f. (1 + x + 2*x^2)/((1 - x)^2*(1 - x^3)).at n=14A000969
- Number of sublattices of index n in generic 3-dimensional lattice.at n=7A001001
- Generalized pentagonal numbers: m*(3*m - 1)/2, m = 0, +-1, +-2, +-3, ....at n=20A001318
- Semiprimes (or biprimes): products of two primes.at n=50A001358
- Generalized Stirling numbers, [n+2,n]_2.at n=4A001701
- Generalized Stirling numbers, [n+5,5]_2.at n=2A001707
- Numbers whose digits contain no loops (version 2).at n=48A001742
- Primes multiplied by 5.at n=10A001750
- The coding-theoretic function A(n,4,3).at n=30A001839
- Expansion of g.f. x/((1 - x)^2*(1 - x^3)).at n=29A001840
- Eighth column of quadrinomial coefficients.at n=2A001919
- a(n) = floor((n+1/2)*(2+sqrt(2))); winning positions in the 2-Wythoff game.at n=45A001954
- v-pile positions of the 4-Wythoff game with i=3.at n=29A001968