7218
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 15678
- Proper Divisor Sum (Aliquot Sum)
- 8460
- 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
- 2400
- Möbius Function
- 0
- Radical
- 2406
- Omega Function (Ω)
- 4
- 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
- no
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 44
- 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
- Smallest positive number that can be written as sum of distinct Fibonacci numbers in n ways.at n=60A013583
- Convolution of Lucas numbers and A023533.at n=17A023623
- Numbers whose base-5 representation contains exactly two 2's and three 3's.at n=24A045273
- Record subsequence of b(3k+2), b()=A048142().at n=30A051058
- Harshad numbers which terminate in their digital sum.at n=43A070938
- Number of cycles in range [A014137(n-1)..A014138(n-1)] of permutation A089865/A089866.at n=10A089844
- Sequence arising from enumeration of domino tilings of Aztec Pillow-like regions.at n=5A092441
- a(n) = a(n-1) XOR Sum_{k=1..n-1} a(k), with a(1)=1, a(2)=3, where XOR is the binary exclusive OR operation.at n=12A099811
- Table of number of domino tilings of generalized Aztec pillows of type (1, ..., 1, 3, 1, ..., 1)_n.at n=26A112830
- Triangle read by rows: numbers of isomers of unbranched a-4-catapolynonagons.at n=40A120650
- Multiples of 18 containing a 18 in their decimal representation.at n=18A121038
- Unbranched a-4-catapolynonagons (see Brunvoll reference for precise definition).at n=4A121127
- Triangular array S(m,n), 1<=n<=m, giving the total number of tossed cards in the card game described in A161135.at n=54A161136
- Main diagonal of the triangular array A161136.at n=9A161138
- Triangle read by rows: T(n,k) is the number of permutations of [n] having k fixed blocks.at n=26A180192
- Number of (n+2) X 3 binary matrices with every 3 X 3 block having exactly four 1's.at n=4A181255
- Number of (n+2)X7 binary matrices with every 3X3 block having exactly four 1's.at n=0A181259
- T(n,k) = number of (n+2) X (k+2) binary matrices with every 3 X 3 block having exactly four 1's.at n=10A181262
- T(n,k) = number of (n+2) X (k+2) binary matrices with every 3 X 3 block having exactly four 1's.at n=14A181262
- Total number of parts that are not the smallest part in all partitions of n that do not contain 1 as a part.at n=32A195821