7545
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 12096
- Proper Divisor Sum (Aliquot Sum)
- 4551
- 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
- 4016
- Möbius Function
- -1
- Radical
- 7545
- 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
- 70
- 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
- Expansion of Product_{k>=1} (1 + 3*x^k).at n=22A032308
- Numbers whose set of base-9 digits is {1,3}.at n=35A032916
- Number of n-digit 7-smooth numbers (A002473).at n=15A085630
- Number of partitions that are "3-close" to being self-conjugate.at n=39A108962
- Expansion of -(1+x^2)/((x^2+4*x+1)*(x^2-2*x-1)).at n=6A111644
- Row sums of triangle A129065 (v=1 member of a family).at n=5A129458
- Partial sum of irregular primes A000928.at n=26A132360
- Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 110-111-011 pattern in any orientation.at n=10A146255
- Number of n X n binary arrays symmetric under horizontal and vertical reflection with all ones connected only in a 1100-0111-1100 pattern in any orientation.at n=14A146676
- n such that the Moebius function take successively, from n, the values -1,0,-1,0,-1,0.at n=38A172354
- Numbers k that 4^k + 13^2 is prime.at n=28A178653
- Numbers m such that the Stern polynomial B(m,x) is self-reciprocal.at n=47A186890
- Number of (n+1) X 2 0..3 arrays containing all values 0..3 with every 2 X 2 subblock having two or four distinct values, and new values 0..3 introduced in row major order.at n=4A210167
- Number of (n+1)X6 0..3 arrays containing all values 0..3 with every 2X2 subblock having two or four distinct values, and new values 0..3 introduced in row major order.at n=0A210171
- T(n,k)=Number of (n+1)X(k+1) 0..3 arrays containing all values 0..3 with every 2X2 subblock having two or four distinct values, and new values 0..3 introduced in row major order.at n=10A210174
- T(n,k)=Number of (n+1)X(k+1) 0..3 arrays containing all values 0..3 with every 2X2 subblock having two or four distinct values, and new values 0..3 introduced in row major order.at n=14A210174
- Starting from a(1)=1, a(n) is the minimum integer greater than a(n-1) such that a(n)+a(n-1), a(n)*a(n-1)+1 and a(n)*a(n-1)-1 are all primes.at n=38A228590
- Numbers k such that k^2 - k - 1, k^3 - k - 1, and k^4 - k - 1 are all prime.at n=28A236171
- Number of partitions of n into 6 parts such that every i-th smallest part (counted with multiplicity) is different from i.at n=35A244242
- Poincaré series for hyperbolic reflection group with Coxeter diagram shown in Comments.at n=18A265049