2505
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
- 1
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 4032
- Proper Divisor Sum (Aliquot Sum)
- 1527
- 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
- 1328
- Möbius Function
- -1
- Radical
- 2505
- 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
- 89
- 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
- Generalized divisor function. Number of partitions of n with exactly three part sizes.at n=32A002134
- Shifts 6 places right under binomial transform.at n=9A010746
- Shifts 6 places left under inverse binomial transform.at n=15A010747
- arcsinh(sec(x)*sinh(x))=x+3/3!*x^3+5/5!*x^5-217/7!*x^7+2505/9!*x^9...at n=4A012817
- a(n) = Sum_{i=1..floor((n+1)/4)} a(2*i-1) * a(n-2*i+1), with a(1)=a(2)=1 and a(3)=5.at n=12A024729
- a(n) = Sum_{i=1..floor((n+2)/4)} a(2i-1)*a(n-2i+1), with a(1)=a(2)=1 and a(3)=5.at n=11A024951
- a(n) = position of 3*n^2 in sequence A025051 (numbers of form j*k + k*i + i*j, without repetitions, where 1 <= i <= j <= k).at n=28A025056
- T(2n,n+2), T given by A026758.at n=5A026873
- Numbers having period-4 6-digitized sequences.at n=7A031197
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 20.at n=4A031698
- Lucky numbers with size of gaps equal to 12 (upper terms).at n=30A031895
- Number of partitions of n with equal number of parts congruent to each of 1, 3 and 4 (mod 5).at n=49A035580
- Number of partitions of n in which no parts are multiples of 5.at n=29A035959
- Friedman numbers: can be written in a nontrivial way using their digits and the operations + - * / ^ and concatenation of digits (but not of results).at n=35A036057
- Reversion of g.f. (beginning with x term) for number of trees with n nodes.at n=10A037247
- Base 4 digits are, in order, the first n terms of the periodic sequence with initial period 2,1,3,0.at n=5A037737
- Numbers having three 3's in base 6.at n=39A043383
- Numbers having three 3's in base 9.at n=21A043467
- Numbers n such that string 1,1 occurs in the base 8 representation of n but not of n-1.at n=39A044196
- Numbers n such that string 8,3 occurs in the base 9 representation of n but not of n-1.at n=33A044326