7543
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 7960
- Proper Divisor Sum (Aliquot Sum)
- 417
- 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
- 7128
- Möbius Function
- 1
- Radical
- 7543
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 114
- 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
- Denominators of approximations to e.at n=27A006259
- Pseudoprimes to base 14.at n=28A020142
- Pseudoprimes to base 35.at n=22A020163
- Pseudoprimes to base 79.at n=33A020207
- Pseudoprimes to base 85.at n=47A020213
- Numbers whose set of base-9 digits is {1,3}.at n=34A032916
- Positive numbers having the same set of digits in base 4 and base 9.at n=40A037427
- Numerators of continued fraction convergents to sqrt(315).at n=6A041594
- Numerators of continued fraction convergents to sqrt(875).at n=10A042690
- Base-9 palindromes that start with 1.at n=32A043028
- Numbers having four 1's in base 9.at n=20A043460
- Numbers whose base-4 representation contains exactly four 1's and three 3's.at n=11A045132
- The next smallest pair of numbers is taken so that a(2n-1)/a(2n) converges to e = exp(1).at n=43A065370
- Numbers k such that Euler phi(k) / Carmichael lambda(k) = 18.at n=39A066697
- a(n) = either 4a(n-1)+1 or 4a(n-1)+3 depending on corresponding term of A005614, +3 for 0, +1 for 1.at n=6A066744
- Number of permutations satisfying -k <= p(i)-i <= r and p(i)-i not in I, i=1..n, with k=1, r=4, I={1,2}.at n=24A079972
- Diagonal of triangular spiral in A051682.at n=40A081270
- Numbers n such that n 7's followed by n is prime.at n=5A084428
- Denominators of "Farey fraction" approximations to e.at n=29A119015
- a(n) = 3 + floor((2 + Sum_{j=1..n-1} a(j))/5).at n=43A120172