1209
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
- 1792
- Proper Divisor Sum (Aliquot Sum)
- 583
- 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
- 720
- Möbius Function
- -1
- Radical
- 1209
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 57
- 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
- a(n) = (10n+1)*(10n+9).at n=3A001535
- Odd squarefree numbers with an odd number of prime factors that have no prime factors greater than 31.at n=49A002556
- a(n) = n*(5*n^2 - 2)/3.at n=9A004466
- Let S denote the palindromes in the language {0,1,2}*; a(n) = number of words of length n in the language SS.at n=8A007056
- Molien series for A_5.at n=33A008628
- Coordination sequence T3 for Zeolite Code iRON.at n=24A009883
- a(n) = Sum_{j=0..n} j*Fibonacci(j).at n=10A014286
- a(n) = (n+2)*(n+1)*(n^2 + 7*n - 12)/24.at n=10A014309
- Partial sums of A001935; at one time this was conjectured to agree with A007478.at n=23A014605
- Number of ordered 5-tuples of integers from [ 1..n ] with no global factor.at n=8A015650
- Positive integers n such that 2^n (mod n) == 2^9 (mod n).at n=56A015931
- Pseudoprimes to base 92.at n=21A020220
- Numbers k such that the continued fraction for sqrt(k) has period 18.at n=32A020357
- Convolution of A023532 and composite numbers.at n=43A023599
- a(n) = floor( (2nd elementary symmetric function of S(n))/(first elementary symmetric function of S(n)) ), where S(n) = {first n+1 positive integers congruent to 1 mod 3}.at n=39A024219
- Numbers that are the sum of 3 nonzero squares in exactly 10 ways.at n=17A025330
- Numbers that are the sum of 3 nonzero squares in 10 or more ways.at n=32A025338
- Numbers that are the sum of 3 distinct nonzero squares in exactly 10 ways.at n=16A025348
- Numbers that are the sum of 3 distinct nonzero squares in 9 or more ways.at n=36A025355
- Numbers that are the sum of 3 distinct nonzero squares in 10 or more ways.at n=24A025356