2142
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 5616
- Proper Divisor Sum (Aliquot Sum)
- 3474
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 576
- Möbius Function
- 0
- Radical
- 714
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 4
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 169
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- A Fielder sequence: a(n) = a(n-1) + a(n-2) - a(n-7), n >= 8.at n=16A001636
- MacMahon's generalized sum of divisors function.at n=13A002128
- Number of solutions to a linear inequality.at n=41A002797
- Numbers n such that n^32 + 1 is prime.at n=42A006315
- Coordination sequence T2 for Zeolite Code AEI.at n=35A008002
- Coordination sequence T6 for Zeolite Code EUO.at n=29A008101
- Coordination sequence T2 for Zeolite Code MAZ.at n=32A008145
- Coordination sequence T5 for Zeolite Code MTW.at n=30A008200
- Coordination sequence for quartz.at n=26A008261
- Coordination sequence for Cr3Si, Cr position.at n=12A009928
- a(n) = floor( n*(n-1)*(n-2)/20 ).at n=36A011902
- Numbers k that divide s(k), where s(1)=1, s(j)=18*s(j-1)+j.at n=39A014868
- Expansion of 1/(1-x^7-x^8-x^9-x^10-x^11-x^12-x^13-x^14-x^15-x^16).at n=46A017865
- a(n) is the concatenation of n and 2n.at n=20A019550
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (Lucas numbers), t = (odd natural numbers).at n=14A024473
- a(n) = sum of the numbers between the two n's in A026346.at n=30A026349
- a(n) = Sum_{k=0..floor(n/2)} A026637(n-k, k).at n=16A026647
- a(n) = n*(n + 9).at n=42A028569
- Expansion of (theta_3(z)*theta_3(5z)+theta_2(z)*theta_2(5z))^3.at n=40A028588
- "CGK" (necklace, element, unlabeled) transform of 2,1,1,1,...at n=21A032157