491
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 14
- Digital Root
- 5
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 492
- 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
- 490
- Möbius Function
- -1
- Radical
- 491
- 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
- 141
- Smith 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
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 94
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Names
- German
- vierhunderteinundneunzig· ordinal: vierhunderteinundneunzigste
- English
- four hundred ninety-one· ordinal: four hundred ninety-first
- Spanish
- cuatrocientos noventa y uno· ordinal: 491º
- French
- quatre cent quatre-vingt-onze· ordinal: quatre cent quatre-vingt-onzième
- Italian
- quattrocentonovantuno· ordinal: 491º
- Latin
- quadringenti nonaginta unus· ordinal: 491.
- Portuguese
- quatrocentos e noventa e um· ordinal: 491º
Appears in sequences
- Primes p == 3, 9, 11 (mod 20) such that 2p+1 is also prime.at n=11A000355
- Irregular primes: primes p such that at least one of the numerators of the Bernoulli numbers B_2, B_4, ..., B_{p-3} (A000367) is divisible by p.at n=27A000928
- Numbers k such that sum of squares of k consecutive integers >= 1 is a square.at n=54A001032
- Primes with primitive root 2.at n=37A001122
- Full reptend primes: primes with primitive root 10.at n=33A001913
- Primes p such that the congruence 2^x == 3 (mod p) is solvable.at n=54A001915
- Primes p such that the congruence 2^x = 5 (mod p) is solvable.at n=51A001916
- Prime determinants of forms with class number 2.at n=43A002052
- Primes of the form 4*k + 3.at n=48A002145
- Let p = A007645(n) be the n-th generalized cuban prime and write p^2 = x^2 + 3*y^2 with y > 0; a(n) = x.at n=45A002367
- Lucasian primes: p == 3 (mod 4) with 2*p+1 prime.at n=13A002515
- Number of simple imperfect squared squares of order n up to symmetry.at n=21A002962
- Primes p with a Fibonacci primitive root g, i.e., such that g^2 = g + 1 (mod p).at n=29A003147
- Numbers that are the sum of 7 positive 5th powers.at n=15A003352
- Inert rational primes in Q(sqrt(-5)).at n=48A003626
- Primes of the form 3n-1.at n=48A003627
- Primes p == +- 3 (mod 8), or, primes p such that 2 is not a square mod p.at n=47A003629
- Inert rational primes in Q(sqrt 7), or, 7 is not a square mod p.at n=47A003632
- Inconsummate numbers in base 10: no number is this multiple of the sum of its digits (in base 10).at n=40A003635
- Inverse Möbius transform of A003964.at n=60A003979