1261
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1372
- Proper Divisor Sum (Aliquot Sum)
- 111
- 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
- 1152
- Möbius Function
- 1
- Radical
- 1261
- 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
- no
- Odd
- yes
Appears in sequences
- Hexanacci numbers with a(0) = ... = a(5) = 1.at n=14A000383
- Flavius Josephus's sieve: Start with the natural numbers; at the k-th sieving step, remove every (k+1)-st term of the sequence remaining after the (k-1)-st sieving step; iterate.at n=39A000960
- Central polygonal numbers: a(n) = n^2 - n + 1.at n=36A002061
- Numbers of the form (p^2 - 1)/120 where p is 1 or prime.at n=34A002381
- Squares written in base 7.at n=21A002440
- Centered 12-gonal numbers, or centered dodecagonal numbers: numbers of the form 6*k*(k-1) + 1.at n=14A003154
- Hex (or centered hexagonal) numbers: 3*n*(n+1)+1 (crystal ball sequence for hexagonal lattice).at n=20A003215
- Divisors of 2^48 - 1.at n=46A003553
- Number of perfect matchings (or domino tilings) in D_4 X P_(n-1).at n=8A003757
- Divisible only by primes congruent to 6 mod 7.at n=38A004624
- Numbers k such that k, k+1 and k+2 have the same number of divisors.at n=23A005238
- Number of ways in which n identical balls can be distributed among 4 boxes in a row such that each pair of adjacent boxes contains at least 4 balls.at n=12A005337
- Pseudoprimes to base 6.at n=7A005937
- Star-hex numbers.at n=2A006062
- Related to series-parallel networks.at n=6A006349
- Coordination sequence T3 for Zeolite Code DAC.at n=22A008069
- Integers that are squarefree and also the sum of first k squarefrees for some k.at n=21A013932
- Generalized Fibonacci numbers.at n=8A015441
- Generalized Fibonacci numbers: a(n) = a(n-1) + 9*a(n-2).at n=6A015445
- a(n) = (9^n-4^n)/5.at n=4A016153