7131
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
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 9512
- Proper Divisor Sum (Aliquot Sum)
- 2381
- 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
- 4752
- Möbius Function
- 1
- Radical
- 7131
- 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
- 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 4-line partitions of n (i.e., planar partitions of n with at most 4 lines).at n=16A002799
- Powers of fifth root of 4 rounded down.at n=32A018123
- Powers of fifth root of 16 rounded down.at n=16A018159
- a(n) = s(1)s(n) + s(2)s(n-1) + ... + s(k)s(n+1-k), where k = [ (n+1)/2 ], s = (1, p(1), p(2), ...).at n=22A024479
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 83.at n=24A031581
- Cycle of 2 steps possible for 'concatenate a(n) and nextprime(a(n)) is a prime'.at n=43A034592
- Moebius transform of A000011 (starting at term 0).at n=19A054183
- A hierarchical sequence (S(W2{2}*c) - see A059126).at n=9A059140
- 1 + sum of first n 4-almost primes.at n=42A110226
- Start with 1015 and repeatedly reverse the digits and add 4 to get the next term.at n=8A117807
- Start with 34 and repeatedly reverse the digits and add 16 to get the next term.at n=11A119454
- Expansion of -x*(3*x^4+9*x^3-29*x^2+12*x-1)/((x-1)*(x^4-3*x^3-27*x^2+12*x-1)).at n=6A123184
- Convolution of A008619 and A001400.at n=27A139672
- Exactly 10 consecutive odd integers starting with n are composite.at n=36A162023
- Number of sequences of n pairs of balanced brackets of three types, round, square, and angle, such that no square brackets are allowed inside matching round brackets.at n=5A165976
- Numbers k that 4^k + 13^2 is prime.at n=27A178653
- Floor-Sqrt transform of Motzkin numbers (A001006).at n=20A192669
- a(n) is the nearest integer to sqrt(pi(10^n)) (see A006880).at n=9A221205
- Number of n X 4 0,1 arrays indicating 2 X 2 subblocks of some larger (n+1) X 5 binary array having a sum of three or less, with rows and columns of the latter in lexicographically nondecreasing order.at n=5A227267
- T(n,k)=Number of nXk 0,1 arrays indicating 2X2 subblocks of some larger (n+1)X(k+1) binary array having a sum of three or less, with rows and columns of the latter in lexicographically nondecreasing order.at n=39A227269