1281
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 1984
- Proper Divisor Sum (Aliquot Sum)
- 703
- 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
- 720
- Möbius Function
- -1
- Radical
- 1281
- Omega Function (Ω)
- 3
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 52
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
Appears in sequences
- Octagonal numbers: n*(3*n-2). Also called star numbers.at n=21A000567
- Moser-de Bruijn sequence: sums of distinct powers of 4.at n=49A000695
- Number of sublattices of index n in generic 3-dimensional lattice.at n=25A001001
- Generalized octagonal numbers: k*(3*k-2), k=0, +- 1, +- 2, +-3, ...at n=41A001082
- Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^7 in powers of x.at n=22A001485
- Numbers that are the sum of 11 positive 7th powers.at n=10A003378
- Numbers that are the sum of 6 nonzero 8th powers.at n=5A003384
- Numbers that are the sum of at most 6 nonzero 8th powers.at n=26A004879
- Numbers that are the sum of at most 7 nonzero 8th powers.at n=31A004880
- Numbers that are the sum of at most 8 nonzero 8th powers.at n=36A004881
- Numbers that are the sum of at most 9 nonzero 8th powers.at n=41A004882
- Triangular numbers plus quarter squares: n*(n+1)/2 + floor(n^2/4) (i.e., A000217(n) + A002620(n)).at n=41A006578
- Reve's puzzle: number of moves needed to solve the Towers of Hanoi puzzle with 4 pegs and n disks, according to the Frame-Stewart algorithm.at n=32A007664
- Coordination sequence T2 for Zeolite Code AFT.at n=27A008027
- Coordination sequence T1 for Zeolite Code MTT.at n=22A008189
- Crystal ball sequence for A_5 lattice.at n=3A008386
- Coordination sequence T2 for Zeolite Code iRON.at n=25A009882
- Irregular triangle read by rows: T(n,k) (n >= 1, 0 <= k <= [n/2]) = number of permutations of 1..n with [n/2]-k runs of consecutive pairs up and down (divided by 2).at n=29A010030
- Pisot sequence E(14,23), a(n) = floor( a(n-1)^2/a(n-2)+1/2 ).at n=9A010902
- Expansion of e.g.f. arctan(arcsin(x) * log(x+1)).at n=7A012307