1226
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1842
- Proper Divisor Sum (Aliquot Sum)
- 616
- 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
- 612
- Möbius Function
- 1
- Radical
- 1226
- 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
- 39
- Smith Number
- no
- Vampire 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
- yes
- Odd
- no
Appears in sequences
- Central polygonal numbers (the Lazy Caterer's sequence): n(n+1)/2 + 1; or, maximal number of pieces formed when slicing a pancake with n cuts.at n=49A000124
- a(n) = least m such that if a/b < c/d where a,b,c,d are integers in [0,n], then a/b < k/m < c/d for some integer k.at n=40A001000
- Number of partitions of n into at most 5 parts.at n=36A001401
- Numbers k such that phi(k) = phi(k+2).at n=25A001494
- Number of rooted planar 2-trees with n nodes.at n=7A001895
- a(n) = n^2 + 1.at n=35A002522
- Number of rooted identity trees with n nodes (rooted trees whose automorphism group is the identity group).at n=13A004111
- a(n) = n^2 + prime(n).at n=32A004232
- Josephus problem: numbers m such that, when m people are arranged on a circle and numbered 1 through m, the final survivor when we remove every 4th person is one of the first three people.at n=19A005427
- a(n) = Sum_{k=1..n-1} (k OR n-k).at n=37A006583
- Numbers k such that phi(k) = phi(sigma(k)).at n=44A006872
- Coordination sequence T1 for Zeolite Code MTN.at n=21A008186
- Coordination sequence T5 for Zeolite Code MTW.at n=23A008200
- Coordination sequence T2 for Cordierite.at n=21A008252
- If a, b in sequence, so is ab+6.at n=19A009307
- Coordination sequence T4 for Zeolite Code RUT.at n=23A009900
- Coefficients in expansion of sqrt(2) as Sum_{n>=1} a(n)/(n*n!*(n+1)!), as found by greedy algorithm.at n=53A011193
- Indices of prime Mersenne numbers (A001348).at n=21A016027
- Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite DOH = Dodecasil 1H [Si34O68].qR starting with a T1 atom.at n=10A019113
- Number of partitions of n into 5 unordered relatively prime parts.at n=36A023025