4001
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 5
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 4002
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 4000
- Möbius Function
- -1
- Radical
- 4001
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 43
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 551
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes p such that the multiplicative order of 2 modulo p is (p-1)/4.at n=27A001134
- Primes of the form 2^q*3^r*5^s + 1.at n=48A002200
- Smallest number that requires n iterations of the unitary totient function (A047994) to reach 1.at n=18A003271
- Primes p == 1 (mod 8), p = a^2 +64*b^2 such that y^2 = x^3 + p*x has rank 0.at n=14A007765
- Coordination sequence T2 for Zeolite Code BOG.at n=45A008050
- Coordination sequence T2 for Zeolite Code LAU.at n=45A008125
- Coordination sequence T2 for Zeolite Code MEI.at n=46A008147
- Numbers k such that k^2 and k have same last 3 digits.at n=17A008853
- Coordination sequence T1 for Zeolite Code VNI.at n=39A009907
- Shallit sequence S(14,23), a(n)=[ a(n-1)^2/a(n-2)+1 ].at n=11A010923
- Numbers k such that the continued fraction for sqrt(k) has period 13.at n=26A020352
- Let q_k=p(p+2) be product of k-th pair of twin primes; sequence gives values of p such that (q_k)^2 > q_{k-i}q_{k+i} for all 1 <= i <= k-1.at n=34A021005
- Initial members of prime triples (p, p+2, p+6).at n=34A022004
- Primes that remain prime through 2 iterations of function f(x) = 9x + 2.at n=47A023265
- Primes p such that p, p+6, p+12, p+18 are all primes.at n=16A023271
- Primes that remain prime through 3 iterations of function f(x) = 9x + 8.at n=14A023298
- n written in fractional base 8/4.at n=33A024646
- Least m such that if r and s in {1/1, 1/4, 1/9,..., 1/n^2} satisfy r < s, then r < k/m < s for some integer k.at n=22A024827
- a(n) = least m such that if r and s in {1/2, 1/4, 1/6, ..., 1/2n} satisfy r < s, then r < k/m < (k+4)/m < s for some integer k.at n=20A024848
- Smallest prime containing n-th square as substring.at n=20A029948