1251
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 9
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 1820
- Proper Divisor Sum (Aliquot Sum)
- 569
- 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
- 828
- Möbius Function
- 0
- Radical
- 417
- Omega Function (Ω)
- 3
- 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
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 26
- 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
- From a fractal set of positive Lebesgue measure, a self-replicating tiling with holes, the 4-reptile following the 2-reptile of Paul Levy.at n=36A000361
- a(n) = n^2 written backwards.at n=38A002942
- Numbers which are the sum of 3 nonzero 4th powers.at n=30A003337
- Apéry numbers: a(n) = Sum_{k=0..n} binomial(n,k)^2 * binomial(n+k,k).at n=4A005258
- Related to Fibonacci numbers.at n=5A006502
- Coordination sequence T10 for Zeolite Code EUO.at n=22A008096
- Crystal ball sequence for A_4 lattice.at n=4A008384
- Let j = | i - i_written_backwards |, k = j + j_written_backwards; then k is in this sequence.at n=15A008920
- "Pascal sweep" for k=6: draw a horizontal line through the 1 at C(k,0) in Pascal's triangle; rotate this line and record the sum of the numbers on it (excluding the initial 1).at n=35A009475
- Coordination sequence T2 for Zeolite Code -CLO.at n=32A009851
- Coordination sequence T1 for Zeolite Code VET.at n=22A009902
- Positive integers n such that 2^n (mod n) == 2^9 (mod n).at n=58A015931
- Expansion of 1/(1-x^10-x^11-x^12-x^13-x^14).at n=69A017890
- Let m=n+1; a(n) is the least positive integer s, not a multiple of m, such that if 1<=d<=m and (d,m)=1, then d divides one of the numbers s-m, s-2m, ..., s-m[ s/m ].at n=45A018205
- a(n+1) (n >= 1) is smallest number > a(n) which is the sum of cubes of distinct earlier terms.at n=29A019511
- a(n) = n*(31*n-1)/2.at n=9A022288
- Expansion of Product_{m>=1} (1 - m*q^m)^9.at n=7A022669
- Numbers with exactly 3 0's in their base 5 expansion.at n=20A023724
- a(n) = least m such that if r and s in {1/2, 1/4, 1/6,..., 1/2n} satisfy r < s, then r < k/m < s for some integer k.at n=28A024820
- Numbers that are the sum of 3 nonzero squares in exactly 9 ways.at n=23A025329