1289
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 1290
- 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
- 1288
- Möbius Function
- -1
- Radical
- 1289
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 145
- 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
- yes
- Mersenne Prime
- no
- Sophie Germain Prime
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 209
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Primes p == 3, 9, 11 (mod 20) such that 2p+1 is also prime.at n=22A000355
- Primes with 6 as smallest primitive root.at n=12A001125
- Lesser of twin primes.at n=43A001359
- Centered 4-dimensional orthoplex numbers (crystal ball sequence for 4-dimensional cubic lattice).at n=6A001846
- Crystal ball sequence for 6-dimensional cubic lattice.at n=4A001848
- Numbers divisible only by primes congruent to 1 mod 7.at n=35A004619
- Class 4- primes (for definition see A005109).at n=30A005112
- Sophie Germain primes p: 2p+1 is also prime.at n=44A005384
- Truncated octahedral numbers: 16*n^3 - 33*n^2 + 24*n - 6.at n=4A005910
- Prime self (or Colombian) numbers: primes not expressible as the sum of an integer and its digit sum.at n=25A006378
- Supersingular primes of the elliptic curve X_0 (11).at n=6A006962
- Primes of form 8n+1, that is, primes congruent to 1 mod 8.at n=47A007519
- Primes p == 1 (mod 8), p = a^2 + 64*b^2 such that y^2 = x^3 + p*x has rank 2.at n=17A007766
- Coordination sequence T3 for Zeolite Code AFT.at n=27A008028
- Coordination sequence T6 for Zeolite Code EUO.at n=22A008101
- Coordination sequence T1 for Zeolite Code MEI.at n=26A008146
- Coordination sequence T2 for Zeolite Code PHI.at n=26A008228
- Coordination sequence T2 for Coesite.at n=19A008268
- Square array of Delannoy numbers D(i,j) (i >= 0, j >= 0) read by antidiagonals.at n=61A008288
- Square array of Delannoy numbers D(i,j) (i >= 0, j >= 0) read by antidiagonals.at n=59A008288