6155
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
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 7392
- Proper Divisor Sum (Aliquot Sum)
- 1237
- 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
- 4920
- Möbius Function
- 1
- Radical
- 6155
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 155
- 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) = a(n-1) + a(n-2) with a(0)=2, a(1)=5. Sometimes called the Evangelist Sequence.at n=16A001060
- a(n) = n^3 + n^2 - 1.at n=17A003777
- a(n) = F(n+1) + L(n), where F(n) and L(n) are Fibonacci and Lucas numbers, respectively.at n=17A013655
- [ exp(1/5)*n! ].at n=6A030973
- Numbers having three 8's in base 9.at n=11A043487
- Discriminants of real quadratic fields with class number 2 and related continued fraction period length of 24.at n=33A051989
- Number of positive integers <= 2^n of form 3 x^2 + 8 y^2.at n=16A054165
- Numbers k such that k^6 == 1 (mod 7^4).at n=15A056092
- Numbers n such that the trajectory of n under the `3x+1' map reaches n - 1.at n=39A070991
- Positions of A080299 in A014486.at n=21A080298
- Least positive integers, all distinct, that satisfy sum(n>0,1/a(n)^z)=0, where z=(60+I*11)/61.at n=14A084804
- Number of nonisomorphic partitions of n on the Ferrers diagram.at n=34A095814
- a(n) = (n+1)*prime(n) + n*prime(n+1).at n=27A097240
- Frequency of the hexadecimal E in the first 10^n hexadecimal digits of Pi.at n=4A099347
- Expansion of (7-2*x) / (1-3*x+x^2).at n=7A100545
- Least j > 1 for n > 0 such that j^2 = (n^2 + 1)*(k^2) + (n^2 + 1)*k + 1 where k sequence = A106230.at n=18A106229
- a(0) = 19; for n>0, successively subtract 5, subtract 3 and double.at n=34A106706
- Triangle, read by rows, where g.f. of row n equals the product of (1-x)^n and the g.f. of the coordination sequence for root lattice B_n, for n >= 0.at n=32A109001
- Positive integers i for which A112049(i) == 6.at n=40A112066
- Number of permutations of length n which avoid the patterns 1432, 2314, 3241.at n=8A116800