6545
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 10368
- Proper Divisor Sum (Aliquot Sum)
- 3823
- 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
- 3840
- Möbius Function
- 1
- Radical
- 6545
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
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
- yes
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 137
- 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
- Tetrahedral (or triangular pyramidal) numbers: a(n) = C(n+2,3) = n*(n+1)*(n+2)/6.at n=33A000292
- a(n) = 1^2 + 3^2 + 5^2 + 7^2 + ... + (2*n-1)^2 = n*(4*n^2 - 1)/3.at n=17A000447
- Tetrahedral numbers written backwards.at n=31A004161
- Binomial coefficient C(5n,n-4).at n=3A004346
- Binomial coefficient C(7n,n-2).at n=3A004370
- Expansion of e.g.f.: 1/cos(sinh(x)) (even-indexed coefficients only).at n=4A009009
- Binomial coefficient C(35,n).at n=3A010951
- Binomial coefficient C(n,32).at n=3A010985
- Orders of cyclotomic polynomials containing a coefficient the absolute value of which is >= 5.at n=26A013593
- Smallest order of cyclotomic polynomial containing n or -n as a coefficient.at n=7A013594
- Smallest order of cyclotomic polynomial containing n or -n as a coefficient.at n=8A013594
- Odd tetrahedral numbers: a(n) = (4*n+1)*(4*n+2)*(4*n+3)/6.at n=8A015219
- Pseudoprimes to base 78.at n=25A020206
- a(n) = n*(27*n + 1)/2.at n=22A022285
- a(n) = 9^n - n^2.at n=4A024103
- n written in fractional base 7/6.at n=26A024643
- Quasi-Carmichael numbers to base -7: squarefree composites n such that prime p|n ==> p+7|n+7.at n=4A029567
- a(n) = (prime(n)-3)*(prime(n)-5)*(prime(n)-7)/48.at n=19A030003
- a(n) = (prime(n) - 1)*(prime(n) - 3)*(prime(n) - 5)/48.at n=18A030004
- Number of partitions of n into parts not of the form 7k, 7k+3 or 7k-3. Also number of partitions such that the differences between parts at distance 2 are greater than 1.at n=47A035939