7515
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 13104
- Proper Divisor Sum (Aliquot Sum)
- 5589
- 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
- 3984
- Möbius Function
- 0
- Radical
- 2505
- Omega Function (Ω)
- 4
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 207
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite MEI = ZSM-18 Nan[AlnSi34-nO68].28H2O (n=2.1-5.7) starting with a T1 atom.at n=12A019145
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 13 ones.at n=17A031781
- Numbers k such that 165*2^k+1 is prime.at n=47A032459
- Number of partitions of n into parts not of the form 23k, 23k+5 or 23k-5. Also number of partitions with at most 4 parts of size 1 and differences between parts at distance 10 are greater than 1.at n=33A035993
- Number of planar maps with n edges up to orientation-preserving duality.at n=6A054935
- Triangle T = A007318*A271703; T(n,m)= Sum_{i=0..n} L'(n,i)*binomial(i,m), m=0..n.at n=23A059110
- Numbers n such that the sum of the prime factors of n equals the product of the digits of n.at n=19A067173
- Numbers k such that phi(sigma(k)+k) = sigma(k).at n=12A068366
- Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n, having k long ascents (i.e., ascents of length at least 2). Rows are of length 1,1,2,2,3,3,... .at n=33A091156
- Multiples of 15 containing a 15 in their decimal representation.at n=37A121035
- Triangle read by rows: T(n,k) is the number of 2-Motzkin paths (i.e., Motzkin paths with blue and red level steps) without red level steps on the x-axis, having length n and k level steps (0 <= k <= n).at n=59A126222
- Composites that are the sum of two, three, four and five consecutive composite numbers.at n=9A151745
- Triangle read by rows: binomial(n-1,k-1)*A001006(k).at n=53A154558
- a(n) = 289n + 1.at n=25A158255
- a(n) = 26*n^2 + 1.at n=17A158549
- Number of pairs of rabbits in month n in the dying rabbits problem, if they become mature after 4 months and give birth to exactly 7 pairs, one per month.at n=31A160333
- Inverse of A164844.at n=31A164881
- Triangle read by rows: a(n,k) = number of permutations in S_n which avoid the pattern 123 and have exactly k descents.at n=52A166073
- The second of a pair of sequences A and B with property that all the differences |a_i - b_j| are distinct - for precise definition see Comments lines in A169677.at n=41A169678
- Numbers n such that 10^n*(8+3*10^n)+3 is prime.at n=11A171719