4781
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 5472
- Proper Divisor Sum (Aliquot Sum)
- 691
- 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
- 4092
- Möbius Function
- 1
- Radical
- 4781
- 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
- 121
- 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
- a(n) is the number of compositions of n in which the maximal part is 3.at n=15A000100
- Smallest number that requires n iterations of the bi-unitary totient function (A116550) to reach 1.at n=36A005424
- Numbers k such that the continued fraction for sqrt(k) has period 58.at n=27A020397
- Least sum of 3 distinct nonzero squares in exactly n ways.at n=27A025415
- a(n) = (d(n) - r(n))/5, where d = A026037 and r is the periodic sequence with fundamental period (1,2,0,2,0).at n=39A026039
- Numbers whose base-2 representation has exactly 11 runs.at n=18A043578
- a(n) = (1/2)*(n-th number whose base-2 representation has exactly 12 runs).at n=20A043686
- Numbers n such that number of runs in the base 2 representation of n is congruent to 1 mod 10.at n=30A043764
- Discriminants of real quadratic fields with class number 1 and related continued fraction period length of 18.at n=34A050967
- a(n+1) = a(n) + a(n minus the number of terms of the same parity as n so far).at n=49A060729
- Numbers k such that floor(k*e) is a square.at n=45A062268
- a(n) = A075443(A075451(n)).at n=19A075452
- Numbers k such that T(k) = T(A072522(k)) + T(A072522(k+1)), T(i) being the triangular numbers.at n=16A080824
- a(n) = number of Egyptian fractions 1 = 1/x_1 + ... + 1/x_k (for any k), with 0 < x_1 <= ... <= x_k = n.at n=19A092666
- a(n) = Sum_{k=0..floor(n/5)} C(n-3*k,2*k) * 2^k.at n=19A098577
- Numbers n such that 4*10^n + 3*R_n + 4 is prime, where R_n = 11...1 is the repunit (A002275) of length n.at n=21A102989
- Numbers k such that A003313(k) = A003313(3*k).at n=29A116459
- Denominators of the continued fraction convergents of the decimal concatenation of the even natural numbers.at n=4A128843
- Positive integers whose sixth power is the sum of seven sixth powers (smallest primitive solutions).at n=11A132410
- Triangle c(n,k) of the numerators of coefficients [x^k] P(n,x) of the polynomials P(n,x) of A129891.at n=61A140749