7145
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
- 8580
- Proper Divisor Sum (Aliquot Sum)
- 1435
- 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
- 5712
- Möbius Function
- 1
- Radical
- 7145
- 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
- 194
- 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
- Number of positive integers <= 2^n of form x^2 + 16*y^2.at n=16A000018
- Number of combinatorial types of simplicial n-dimensional polytopes with n+3 nodes.at n=14A000943
- sech(sec(x)*sinh(x))=1-1/2!*x^2-11/4!*x^4-37/6!*x^6+7145/8!*x^8...at n=4A012820
- Conjecturally, number of infinitely-recurring prime patterns on n consecutive integers.at n=31A023192
- Smallest number which can be written as the sum of distinct Fibonacci numbers in n ways and such that the Zeckendorf representation of the number uses only even-subscripted Fibonacci numbers.at n=41A046815
- Number of n-crossing links with alternating braids of 3 strands.at n=15A094029
- Number of n-crossing 2 component links with alternating braids of 3 strands.at n=15A094031
- Number of permutations of length n which avoid the patterns 123 and 4312.at n=19A116699
- A sequence related to M-partitions.at n=50A117117
- Number of isolated primes < 10^n.at n=4A129542
- Prime numbers concatenated with 45.at n=19A137521
- a(n) = 8 - 12*n + 5*n^2.at n=38A145995
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 0), (1, -1, 0), (1, -1, 1), (1, 1, -1), (1, 1, 1)}.at n=7A149788
- Numerator of Euler(n, 13/31).at n=3A157710
- a(n) = 5*a(n-1) + a(n-2); with a(1)=5, a(2)=1.at n=6A189745
- The sum of the largest preimage over all functions f:{1,2,...,n}->{1,2,...,n}.at n=5A208250
- Number of n X 2 0..7 arrays with no element equal to another at a city block distance of exactly two, and new values 0..7 introduced in row major order.at n=4A222891
- T(n,k)=Number of nXk 0..7 arrays with no element equal to another at a city block distance of exactly two, and new values 0..7 introduced in row major order.at n=16A222894
- T(n,k)=Number of nXk 0..7 arrays with no element equal to another at a city block distance of exactly two, and new values 0..7 introduced in row major order.at n=19A222894
- G.f.: (1 + 5*x + 5*x^2 + x^3)/Product_{i=1..10} (1 - x^i).at n=22A256977