921
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1232
- Proper Divisor Sum (Aliquot Sum)
- 311
- 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
- 612
- Möbius Function
- 1
- Radical
- 921
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 129
- Smith 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
Names
- German
- neunhunderteinundzwanzig· ordinal: neunhunderteinundzwanzigste
- English
- nine hundred twenty-one· ordinal: nine hundred twenty-first
- Spanish
- novecientos veintiuno· ordinal: 921º
- French
- neuf cent vingt et un· ordinal: neuf cent vingt et unième
- Italian
- novecentoventuno· ordinal: 921º
- Latin
- nongenti viginti unus· ordinal: 921.
- Portuguese
- novecentos e vinte e um· ordinal: 921º
Appears in sequences
- Numbers beginning with letter 'n' in English.at n=33A000981
- Expansion of x/((1-x)(1-4x^2)(1-5x)).at n=4A002041
- Numbers that are the sum of 9 positive 5th powers.at n=33A003354
- Numbers that are the sum of 4 positive 6th powers.at n=8A003360
- Numbers that are the sum of at most 4 nonzero 6th powers.at n=24A004855
- Numbers that are the sum of at most 5 nonzero 6th powers.at n=33A004856
- Numbers that are the sum of at most 6 nonzero 6th powers.at n=43A004857
- Numbers k such that k, k+1 and k+2 have the same number of divisors.at n=19A005238
- Site percolation series for directed cubic lattice.at n=10A006837
- Coordination sequence T1 for Zeolite Code AEL.at n=20A008004
- Coordination sequence T2 for Zeolite Code AFO.at n=20A008016
- Coordination sequence T7 for Zeolite Code EUO.at n=19A008102
- Expansion of g.f.: 1/((1-x^2)*(1-x^3)*(1-x^5)*(1-x^6)*(1-x^9)).at n=65A008666
- Dates of birth of Kings Louis I, II, ... of France.at n=3A008746
- Number of partitions of {1, 2, ..., 2n} into pairs whose differences are primes.at n=7A009692
- Coordination sequence T3 for Zeolite Code RSN.at n=20A009887
- Coefficients in expansion of e as Sum_{n>=1} a(n)/(n*n!*(n+1)!), as found by greedy algorithm.at n=40A011189
- G.f.: (1+x)*(1+x^3)*(1+x^5)*(1+x^7)*(1+x^9)/((1-x^2)*(1-x^4)*(1-x^6)*(1-x^8)*(1-x^10)).at n=37A014670
- Coordination sequence T4 for Zeolite Code CGF.at n=21A019454
- Numbers k such that the continued fraction for sqrt(k) has period 34.at n=2A020373