5205
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 8352
- Proper Divisor Sum (Aliquot Sum)
- 3147
- 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
- 2768
- Möbius Function
- -1
- Radical
- 5205
- Omega Function (Ω)
- 3
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 28
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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) = floor( n*(n-1)*(n-2)/27 ).at n=53A011909
- Number of partitions of 1/n into 4 reciprocals of positive integers.at n=12A020327
- [ (4th elementary symmetric function of P(n))/(2nd elementary symmetric function of P(n)) ], where P(n) = {first n+3 primes}.at n=11A024456
- Numbers having period-4 6-digitized sequences.at n=26A031197
- Conjecturally, largest attractor in '3x+(2n+1)' problem.at n=37A039515
- Numbers whose base-2 representation has exactly 11 runs.at n=22A043578
- a(n) = (1/2)*(n-th number whose base-2 representation has exactly 12 runs).at n=24A043686
- Numbers n such that number of runs in the base 2 representation of n is congruent to 1 mod 10.at n=34A043764
- McKay-Thompson series of class 18a for Monster.at n=48A058536
- McKay-Thompson series of class 18d for the Monster group.at n=16A058539
- Numbers k such that k and its reversal are both multiples of 15.at n=20A062905
- Non-palindromic number and its reversal are both multiples of 15.at n=15A062914
- Sum of first n^2 odd primes (=S) is divisible by n and S/n = n mod 2.at n=6A064013
- a(n) = ((6*n+37)*4^n - 1)/3.at n=4A072259
- a(n) = Sum_{d|n} d*2^(d-1) for n > 0.at n=10A083413
- a(1)=1 (first row) and then the n-th row of this triangle contains the least set of n unused natural numbers whose sum is k * the sum of the previous row, with k being an integer > 1.at n=65A094280
- The rightmost column of triangle A094280.at n=10A094282
- Number of rooted trees with total weight n, where the weight of a node at height k is k (with the root considered to be at level 1).at n=46A117357
- Numbers k such that k and k^2 use only the digits 0, 2, 5, 7 and 9.at n=22A136917
- (n^3 - n + 15)/3.at n=24A155757