1387
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1480
- Proper Divisor Sum (Aliquot Sum)
- 93
- 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
- 1296
- Möbius Function
- 1
- Radical
- 1387
- Omega Function (Ω)
- 2
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 65
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
Appears in sequences
- 10-gonal (or decagonal) numbers: a(n) = n*(4*n-3).at n=19A001107
- Fermat pseudoprimes to base 2, also called Sarrus numbers or Poulet numbers.at n=4A001567
- Hex (or centered hexagonal) numbers: 3*n*(n+1)+1 (crystal ball sequence for hexagonal lattice).at n=21A003215
- Divisors of 2^18 - 1.at n=19A003528
- a(n) = ceiling(1000*log(n)).at n=3A004242
- Number of 2n-bead black-white reversible necklaces with n black beads.at n=9A005648
- Composite but smallest prime factor >= 17.at n=49A008367
- Coordination sequence T3 for Zeolite Code VNI.at n=23A009909
- Discriminants of imaginary quadratic fields with class number 4 (negated).at n=49A013658
- Coordination sequence T3 for Zeolite Code TER.at n=25A016435
- Expansion of 1/(1-x^8-x^9-x^10-x^11-x^12-x^13-x^14-x^15-x^16-x^17).at n=49A017875
- Expansion of 1/(1-x^9-x^10-x^11-x^12-x^13-x^14-x^15-x^16-x^17-x^18).at n=54A017885
- Number of rational knots (or two-bridge knots) with n crossings (up to mirroring).at n=12A018240
- Define the sequence S(a(0),a(1)) by a(n+2) is the least integer such that a(n+2)/a(n+1) > a(n+1)/a(n) for n >= 0. This is S(4,28).at n=3A019482
- Fermat pseudoprimes to base 4.at n=12A020136
- Pseudoprimes to base 8.at n=24A020137
- Pseudoprimes to base 9.at n=20A020138
- Pseudoprimes to base 16.at n=17A020144
- Pseudoprimes to base 18.at n=16A020146
- Pseudoprimes to base 32.at n=23A020160