1009
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 1010
- Proper Divisor Sum (Aliquot Sum)
- 1
- 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
- 1008
- Möbius Function
- -1
- Radical
- 1009
- Omega Function (Ω)
- 1
- Little Omega Function (ω)
- 1
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
- 111
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- yes
- Composite Number
- no
- Semiprime
- no
- Squarefree Number
- yes
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 169
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Number of points of norm <= n^2 in square lattice.at n=18A000328
- Primes p of the form 3k+1 such that -sqrt(p) < sum_{x=1..p} cos(2*Pi*x^3/p) < sqrt(p).at n=22A000922
- Flavius Josephus's sieve: Start with the natural numbers; at the k-th sieving step, remove every (k+1)-st term of the sequence remaining after the (k-1)-st sieving step; iterate.at n=35A000960
- Numbers that are the sum of 3 nonnegative cubes in more than 1 way.at n=5A001239
- Genus of modular group Gamma(n) = genus of modular curve Chi(n).at n=32A001767
- Prime numbers of measurement.at n=30A002049
- Pseudo-squares: a(n) = the least nonsquare positive integer which is 1 mod 8 and is a (nonzero) quadratic residue modulo the first n odd primes.at n=3A002189
- Smallest prime p of form p = 8k+1 such that first n primes (p_1=2, ..., p_n) are quadratic residues mod p.at n=3A002224
- Number of polygonal graphs.at n=20A002560
- Numbers that are the sum of 10 positive 5th powers.at n=39A003355
- Smallest n-digit prime.at n=3A003617
- Numbers that are a sum of distinct positive cubes in more than one way.at n=39A003998
- Divisible only by primes congruent to 4 mod 5.at n=42A004618
- Numbers divisible only by primes congruent to 1 mod 7.at n=30A004619
- Numbers divisible only by primes congruent to 1 mod 8.at n=40A004625
- Primes p such that 2p-1 is also prime.at n=35A005382
- Related to representations as sums of Fibonacci numbers.at n=50A006132
- Emirps (primes whose reversal is a different prime).at n=36A006567
- From a partition of the integers.at n=22A006628
- Number of subwords of length n in infinite word generated by a -> aab, b -> b.at n=48A006697