4218
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 9120
- Proper Divisor Sum (Aliquot Sum)
- 4902
- 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
- 1296
- Möbius Function
- 1
- Radical
- 4218
- Omega Function (Ω)
- 4
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 82
- 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
- yes
- Odd
- no
Appears in sequences
- Number of column-strict plane partitions of n.at n=13A005986
- Expansion of (1+x^2)/((1-x)^2*(1-x^2)^2).at n=35A005993
- a(n) = n*(n+1)*(2*n+1)/3.at n=18A006331
- If n mod 2 = 0 then n*(n^2-4)/12 else n*(n^2-1)/12.at n=37A006584
- a(n) = floor(n*(n-1)*(n-2)/12).at n=38A011894
- a(n) = floor(n*(n-1)*(n-2)/13).at n=39A011895
- a(n) = 1*(n) + 2*(n-1) + 3*(n-2) + ... + (n+1-k)*k, where k = floor((n+1)/2).at n=35A023855
- a(n) = 1*(n+1-1) + 2*(n+1-2) + ... + k*(n+1-k), where k = floor((n+1)/2).at n=34A023856
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (F(2), F(3), ...), t = A000201 (lower Wythoff sequence).at n=18A024593
- 6 times triangular numbers: a(n) = 3*n*(n+1).at n=37A028896
- a(n) = C(n+3,4) + 3*C(n+1,3) + 5*C(n-1,2) + 7*n - 15.at n=12A034858
- a(n) = C(n+3,4) + 3*C(n+1,3) + 5*C(n-1,2) + 7*n - 15 for n >= 3; a(1)=1, a(2)=10.at n=13A034859
- Numbers having four 3's in base 5.at n=21A043364
- Numbers which, when expressed as a sum of distinct primes with maximum product, use a non-maximal number of primes.at n=19A053020
- Numbers k such that 2*6^k - 1 is prime.at n=33A057472
- a(n) = Sum_{k = 1..n, gcd(k,n)=1} k*(n-k).at n=37A057789
- Numbers which are the sum of their proper divisors containing the digit 0.at n=17A059461
- Triangular spiral sequence: sequence is written as a triangular spiral, each entry is the sum of the row in the previous direction containing the previous entry.at n=26A063177
- a(n) = lcm(n, n+1, n+2)/6.at n=35A067046
- Integers which have at least two different factorizations into coprime parts whose sum are equal.at n=10A069064