7217
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
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8256
- Proper Divisor Sum (Aliquot Sum)
- 1039
- 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
- 6180
- Möbius Function
- 1
- Radical
- 7217
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 44
- 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
- T(2n,n+3), T given by A026747.at n=5A026863
- Numbers whose set of base-15 digits is {1,2}.at n=27A032935
- Number of partitions of n into parts not a multiple of 7. Also number of partitions with at most 6 parts of size 1 and differences between parts at distance 9 are greater than 1.at n=33A035985
- Numbers whose base-5 representation contains exactly three 2's and two 3's.at n=28A045276
- a(1) = 6; a(n) is smallest number >= a(n-1) such that the juxtaposition a(1)a(2)...a(n) is a prime.at n=43A046256
- Number of different Euler multigraphs with n edges, loops forbidden.at n=12A068592
- a(n) = Sum_{k=1..n^2} A078446(k).at n=8A078501
- Sum of the primes in ordered 3 X 3 prime squares.at n=15A105089
- Start with 1015 and repeatedly reverse the digits and add 4 to get the next term.at n=7A117807
- Start with 1027 and repeatedly reverse the digits and add 16 to get the next term.at n=1A119455
- Start with 1013 and repeatedly reverse the digits and add 2 to get the next term.at n=15A120214
- Triangular array S(m,n), 1<=n<=m, giving the total number of tossed cards in the card game described in A161135.at n=53A161136
- Number of binary strings of length n with no substrings equal to 0001 0100 or 1101.at n=15A164467
- a(n) = 4*n^2 + 4*n - 7.at n=41A166147
- Number of increasing sequences of n integers x(1),...,x(n) with values in 1..2*n such that x(j) divides x(k) if j divides k.at n=40A180384
- Least number having exactly two odd prime factors that differ by 2^n.at n=9A190358
- Triangle of coefficients of polynomials u(n,x) jointly generated with A209171; see the Formula section.at n=39A209170
- Numerator of Sum_{k=1..n}(-1)^k/phi(k), where phi = A000010.at n=48A211177
- Numbers of the form (4k+3)^2+4 or (4k+5)^2-8.at n=41A214393
- a(n) = 7*n^2 + 2*n - 15.at n=31A239796