2491
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 2592
- Proper Divisor Sum (Aliquot Sum)
- 101
- 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
- 2392
- Möbius Function
- 1
- Radical
- 2491
- 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
- 102
- 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
- Convolution of A000203 with itself.at n=16A000385
- G.f.: -1 + Product_{k>=1} (1 + prime(k)*x^prime(k)).at n=27A002099
- Products of 2 successive primes.at n=14A006094
- Poincaré series [or Poincare series] for depths of roots in a certain root system.at n=16A019528
- Coordination sequence T2 for Zeolite Code SAO.at n=39A019572
- Numbers k such that the continued fraction for sqrt(k) has period 30.at n=37A020369
- a(n) = [ a(n-1)/a(1) + a(n-2)/a(2) + ... + a(1)/a(n-1) ], for n >= 3.at n=24A022869
- [ 4th elementary symmetric function of {sqrt(k)} ], k = 1,2,...,n.at n=5A025195
- Index of 10^n within the sequence of the numbers of the form 3^i*10^j.at n=48A025741
- Product of next 2 primes after n.at n=42A030661
- Product of next 2 primes after n.at n=45A030661
- Product of next 2 primes after n.at n=44A030661
- Product of next 2 primes after n.at n=43A030661
- Product of largest prime <= n and smallest prime >= n.at n=49A030664
- Product of largest prime <= n and smallest prime >= n.at n=48A030664
- Product of largest prime <= n and smallest prime >= n.at n=50A030664
- Lucky numbers with size of gaps equal to 12 (upper terms).at n=29A031895
- Squares of primes or products of pairs of consecutive primes.at n=29A033476
- Odd k for which k+2^m is composite for all m < k.at n=2A033919
- Fractional part of square root of a(n) starts with 9: first term of runs.at n=44A034115