909
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- yes
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 1326
- Proper Divisor Sum (Aliquot Sum)
- 417
- 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
- 600
- Möbius Function
- 0
- Radical
- 303
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 15
- Smith 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
Names
- German
- neunhundertneun· ordinal: neunhundertneunste
- English
- nine hundred nine· ordinal: nine hundred ninth
- Spanish
- novecientos nueve· ordinal: 909º
- French
- neuf cent neuf· ordinal: neuf cent neufième
- Italian
- novecentonove· ordinal: 909º
- Latin
- nongenti novem· ordinal: 909.
- Portuguese
- novecentos e nove· ordinal: 909º
Appears in sequences
- Numbers beginning with letter 'n' in English.at n=21A000981
- Numbers in which every digit contains at least one loop (version 1).at n=51A001743
- Add 4, then reverse digits; start with 0.at n=18A003608
- Divisible only by primes congruent to 3 mod 7.at n=53A004621
- P-positions in Epstein's Put or Take a Square game.at n=27A005240
- Centered dodecahedral numbers.at n=4A005904
- Pseudoprimes to base 10.at n=10A005939
- Add 2, then reverse digits!.at n=27A007396
- Coordination sequence T1 for Zeolite Code KFI.at n=23A008123
- Coordination sequence T4 for Zeolite Code PAU.at n=22A008222
- Coordination sequence T2 for Cordierite.at n=18A008252
- Numbers that do not contain the letter 't'.at n=54A008523
- Expansion of (1+x^8)/((1-x)*(1-x^2)*(1-x^3)*(1-x^4)).at n=39A008769
- Let j = | i - i_written_backwards |, k = j + j_written_backwards; then k is in this sequence.at n=12A008920
- Coordination sequence T1 for Zeolite Code -CHI.at n=19A009846
- a(n) = 9*a(n-1) + 10*a(n-2).at n=4A015585
- Positive integers n such that 2^n (mod n) == 2^9 (mod n).at n=47A015931
- Add 4, then reverse digits; start with 3.at n=51A016081
- Add 4, then reverse the decimal digits; start with 10.at n=29A016082
- Powers of fifth root of 3 rounded up.at n=31A018122