1961
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 2052
- Proper Divisor Sum (Aliquot Sum)
- 91
- 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
- 1872
- Möbius Function
- 1
- Radical
- 1961
- 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
- 174
- 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
- Number of points of norm <= n^2 in square lattice.at n=25A000328
- Strobogrammatic numbers: the same upside down.at n=23A000787
- McKay-Thompson series of class 11A for the Monster group with a(0) = -5.at n=8A003295
- Les Marvin sequence: a(n) = F(n) + (n-1)*F(n-1), F() = Fibonacci numbers.at n=12A007502
- Coordination sequence T7 for Zeolite Code MTW.at n=29A008202
- Coordination sequence T3 for Zeolite Code NON.at n=27A008214
- Coordination sequence T2 for Scapolite.at n=28A008263
- Year of birth of n-th President of U.S.A.at n=43A008745
- Coordination sequence T1 for Zeolite Code -CHI.at n=28A009846
- Coordination sequence T2 for Zeolite Code -PAR.at n=31A009856
- Coordination sequence T4 for Zeolite Code ZON.at n=31A009922
- Strobogrammatic numbers: numbers that are the same upside down (using calculator-style numerals).at n=47A018846
- Define the sequence S(a(0),a(1)) by a(n+2) is the least integer such that a(n+2)/a(n+1) > a(n+1)/a(n) for n >= 0. This is S(3,15) (agrees with A019478 only for n <= 23).at n=4A019477
- a(n) = 5*a(n-1) + a(n-2) - 3*a(n-3).at n=4A019478
- Fibonacci sequence beginning 1, 13.at n=12A022103
- Number of 1's in n-th term of A022470.at n=28A022472
- a(n) = Sum_{k=1..n} (n-k) * floor(n/k).at n=26A024920
- a(n) = (1/2)*A014431(n+2).at n=8A025235
- (d(n)-r(n))/5, where d = A008778 and r is the periodic sequence with fundamental period (0,3,1,0,1).at n=35A026053
- Expansion of (1+x^2-x^3)/(1-x)^4.at n=20A027378