1687
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1936
- Proper Divisor Sum (Aliquot Sum)
- 249
- 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
- 1440
- Möbius Function
- 1
- Radical
- 1687
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 42
- 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
- Number of partitions into non-integral powers.at n=10A000339
- Expansion of (Product_{j>=1} (1-(-x)^j) - 1)^7 in powers of x.at n=24A001485
- Divisors of 2^24 - 1.at n=40A003532
- G.f.: Product_{k>=1} (1 + x^(2*k - 1)) / (1 - x^(2*k)).at n=33A006950
- Coordination sequence T2 for Zeolite Code BRE.at n=27A008059
- Coordination sequence T1 for Zeolite Code LTL.at n=30A008138
- Coordination sequence T4 for Zeolite Code PAU.at n=30A008222
- Coordination sequence T1 for Scapolite.at n=26A008262
- Coordination sequence T2 for Zeolite Code RTE.at n=28A009891
- a(n) = floor(n*(n-1)*(n-2)/30).at n=38A011912
- Positive integers n such that 2^n == 2^7 (mod n).at n=46A015927
- Pseudoprimes to base 15.at n=6A020143
- Pseudoprimes to base 16.at n=19A020144
- Strong pseudoprimes to base 15.at n=0A020241
- Numbers k such that the continued fraction for sqrt(k) has period 20.at n=42A020359
- n-th composite is sum of first k composites for some k.at n=40A020642
- Numbers k such that Fib(k) == 13 (mod k).at n=14A023178
- Convolution of natural numbers with (1, p(1), p(2), ... ), where p(k) is the k-th prime.at n=15A023538
- s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = A023532, t = (odd natural numbers).at n=53A024372
- a(n) = [ (2nd elementary symmetric function of S(n))/(first elementary symmetric function of S(n)) ], where S(n) = {first n+1 positive integers congruent to 1 mod 4}.at n=40A024385