1555
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1872
- Proper Divisor Sum (Aliquot Sum)
- 317
- 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
- 1240
- Möbius Function
- 1
- Radical
- 1555
- 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
- 34
- 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) = (6^n - 1)/5.at n=5A003464
- Weighted count of partitions with distinct parts.at n=23A005895
- Array (a frieze pattern) defined by a(n,k) = (a(n-1,k)*a(n-1,k+1) - 1) / a(n-2,k+1), read by antidiagonals.at n=40A007754
- Coordination sequence T2 for Zeolite Code AFO.at n=26A008016
- Coordination sequence T2 for Zeolite Code NON.at n=24A008213
- A B_2 sequence: a(n) = least value such that the sequence increases and pairwise sums of distinct terms are all distinct.at n=33A010672
- Discriminants of imaginary quadratic fields with class number 4 (negated).at n=53A013658
- Numbers k that divide s(k), where s(1)=1, s(j)=6*s(j-1)+j.at n=44A014853
- Numbers k that divide 6^k-1.at n=5A014946
- q-Fibonacci numbers for q=6, scaling a(n-2).at n=5A015463
- Cyclotomic polynomials at x=6.at n=5A019324
- Numbers k such that the continued fraction for sqrt(k) has period 32.at n=19A020371
- Cyclotomic polynomials at x=-6.at n=10A020505
- Expansion of (1+x^10)/((1-x)*(1-x^2)*(1-x^3)*(1-x^5)).at n=51A020702
- Fibonacci sequence beginning 4, 15.at n=11A022133
- Triangle of Gaussian binomial coefficients [ n,k ] for q = 6.at n=19A022170
- Triangle of Gaussian binomial coefficients [ n,k ] for q = 6.at n=16A022170
- Gaussian binomial coefficients [ n,4 ] for q = 6.at n=1A022222
- a(n) = n*(31*n + 1)/2.at n=10A022289
- Expansion of Product_{m >= 1} (1 + q^m)^(-2).at n=40A022597