285
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 480
- Proper Divisor Sum (Aliquot Sum)
- 195
- 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
- 144
- Möbius Function
- -1
- Radical
- 285
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 104
- Smith 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
Names
- German
- zweihundertfünfundachtzig· ordinal: zweihundertfünfundachtzigste
- English
- two hundred eighty-five· ordinal: two hundred eighty-fifth
- Spanish
- doscientos ochenta y cinco· ordinal: 285º
- French
- deux cent quatre-vingt-cinq· ordinal: deux cent quatre-vingt-cinqième
- Italian
- duecentoottantacinque· ordinal: 285º
- Latin
- ducenti octoginta quinque· ordinal: 285.
- Portuguese
- duzentos e oitenta e cinco· ordinal: 285º
Appears in sequences
- Square pyramidal numbers: a(n) = 0^2 + 1^2 + 2^2 + ... + n^2 = n*(n+1)*(2*n+1)/6.at n=9A000330
- Related to cumulative height of rooted plane trees.at n=5A000758
- Number of cubic bicolored graphs on n unlabeled nodes admitting an automorphism exchanging the colors.at n=9A000840
- Lucky numbers.at n=53A000959
- n! never ends in this many 0's.at n=55A000966
- Numbers that are divisible by at least three different primes.at n=53A000977
- Moran numbers: k such that k/(sum of digits of k) is prime.at n=26A001101
- Erroneous version of A002572.at n=12A001180
- a(n) = 1^n + 2^n + ... + 9^n.at n=2A001556
- The coding-theoretic function A(n,4,4).at n=16A001843
- Sorting numbers: maximal number of comparisons for sorting n elements by binary insertion.at n=57A001855
- v-pile counts for the 4-Wythoff game with i=2.at n=54A001966
- Number of partitions of floor(7n/2)-1 into n nonnegative integers each no greater than 7.at n=8A001980
- Number of partitions of 4n-1 into n nonnegative integers each no greater than 8.at n=7A001982
- Numbers dividing A002037(i) and larger than A002037(i-1), for some i>0.at n=24A002038
- a(n) = least value of m for which Liouville's function A002819(m) = -n.at n=19A002053
- a(n) = binomial(5*n, n)/(4*n + 1).at n=4A002294
- Numbers y such that p^2 = x^2 + y^2, 0 < x < y, p = A002144(n).at n=28A002365
- Odd squarefree numbers with an odd number of prime factors that have no prime factors greater than 31.at n=16A002556
- Number of partitions of 1 into n powers of 1/2; or (according to one definition of "binary") the number of binary rooted trees.at n=12A002572