27
domain: N
Properties
Digital Properties
- Digit Count
- 2
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 40
- Proper Divisor Sum (Aliquot Sum)
- 13
- 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
- 18
- Möbius Function
- 0
- Radical
- 3
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 1
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
- yes
- 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
- 111
- Smith Number
- yes
Classification
- Natural
- yes
- Even
- no
- Odd
- yes
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- yes
- Achilles Number
- no
- Perfect Power
- yes
- Smooth Number
- yes
- Carmichael Number
- no
Names
- German
- siebenundzwanzig· ordinal: siebenundzwanzigste
- English
- twenty-seven· ordinal: twenty-seventh
- Spanish
- veintisiete· ordinal: 27º
- French
- vingt-sept· ordinal: vingt-septième
- Italian
- ventisette· ordinal: 27º
- Latin
- viginti septem· ordinal: 27.
- Portuguese
- vinte e sete· ordinal: 27º
Appears in sequences
- Expansion of Product_{m >= 1} (1 + x^m); number of partitions of n into distinct parts; number of partitions of n into odd parts.at n=15A000009
- Smallest prime power >= n.at n=25A000015
- Smallest prime power >= n.at n=26A000015
- The positive integers. Also called the natural numbers, the whole numbers or the counting numbers, but these terms are ambiguous.at n=26A000027
- Let A(n) = #{(i,j): i^2 + j^2 <= n}, V(n) = Pi*n, P(n) = A(n) - V(n); A000099 gives values of n where |P(n)| sets a new record; sequence gives closest integer to P(A000099(n)).at n=21A000036
- Numbers that are not squares (or, the nonsquares).at n=21A000037
- Numbers k such that (2k)^4 + 1 is prime.at n=10A000059
- Number of signed trees with n nodes.at n=4A000060
- A Beatty sequence: a(n) = floor(n/(e-2)).at n=19A000062
- a(n) = floor(n^(3/2)).at n=9A000093
- a(n) = n*(n+3)/2.at n=6A000096
- a(n) = number of compositions of n in which the maximum part size is 4.at n=8A000102
- A nonlinear binomial sum.at n=5A000126
- Positive zeros of Bessel function of order 0 rounded to nearest integer.at n=8A000134
- Number of solutions to x^4 == 0 (mod n).at n=80A000190
- Lower Wythoff sequence (a Beatty sequence): a(n) = floor(n*phi), where phi = (1+sqrt(5))/2 = A001622.at n=16A000201
- a(8i+j) = 13i + a(j), where 1<=j<=8.at n=16A000202
- Number of inequivalent ways of dissecting a regular (n+2)-gon into n triangles by n-1 non-intersecting diagonals under rotations and reflections; also the number of (unlabeled) maximal outerplanar graphs on n+2 vertices.at n=6A000207
- A Beatty sequence: floor(n*(e-1)).at n=15A000210
- a(n) = floor(n^2/3).at n=9A000212