11987
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 26
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 11988
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 11986
- Möbius Function
- -1
- Radical
- 11987
- 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
- 81
- 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
- 1438
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Lower prime of a difference of 20 between consecutive primes.at n=25A031938
- Primes of the form 666*k - 1.at n=6A063472
- Numbers n such that the absolute value of the real part of (1+2*I)^n is prime.at n=20A073019
- First occurrence of primes in the progression k*x^2-1.at n=32A090688
- Number of A095745-primes in range ]2^n,2^(n+1)].at n=19A095755
- Primes of the form 210k + 17.at n=28A140842
- Primes congruent to 36 mod 37.at n=39A142145
- Primes congruent to 15 mod 41.at n=28A142212
- Primes congruent to 33 mod 43.at n=36A142282
- Primes congruent to 2 mod 47.at n=26A142355
- Primes congruent to 31 mod 49.at n=36A142440
- Primes congruent to 9 mod 53.at n=30A142539
- Primes congruent to 52 mod 55.at n=31A142638
- Primes congruent to 17 mod 57.at n=37A142676
- Primes congruent to 10 mod 59.at n=26A142737
- Primes congruent to 31 mod 61.at n=29A142829
- Primes congruent to 17 mod 63.at n=40A142898
- Number of ways to place zero or more nonadjacent 1,0 1,1 2,1 3,1 4,2 5,2 polyhexes in any orientation on a planar nXnXn triangular grid.at n=6A155290
- a(n) = 324n - 1.at n=36A158306
- Numbers n such that 10^n - 81 is prime.at n=14A178437