990
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 2808
- Proper Divisor Sum (Aliquot Sum)
- 1818
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 240
- Möbius Function
- 0
- Radical
- 330
- Omega Function (Ω)
- 5
- Little Omega Function (ω)
- 4
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- yes
- 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
- 98
- Smith Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Names
- German
- neunhundertneunzig· ordinal: neunhundertneunzigste
- English
- nine hundred ninety· ordinal: nine hundred ninetieth
- Spanish
- novecientos noventa· ordinal: 990º
- French
- neuf cent quatre-vingt-dix· ordinal: neuf cent quatre-vingt-dixième
- Italian
- novecentonovanta· ordinal: 990º
- Latin
- nongenti nonaginta· ordinal: 990.
- Portuguese
- novecentos e noventa· ordinal: 990º
Appears in sequences
- Let A(n) = #{(i,j,k): i^2 + j^2 + k^2 <= n}, V(n) = (4/3)Pi*n^(3/2), P(n) = A(n) - V(n); sequence gives values of n where |P(n)| sets a new record.at n=25A000092
- Smallest even number that is an unordered sum of two odd primes in exactly n ways.at n=52A001172
- Triangular numbers of form a(a+1)(a+2).at n=4A001219
- Number of inequivalent Costas arrays of order n under dihedral group.at n=11A001441
- Triangle of coefficients of Bessel polynomials (exponents in decreasing order).at n=52A001497
- Triangle a(n,k) (n >= 0, 0 <= k <= n) of coefficients of Bessel polynomials y_n(x) (exponents in increasing order).at n=47A001498
- a(n) = (4*n+1)*(4*n+2)*(4*n+3).at n=2A001505
- Related to Zarankiewicz's problem.at n=42A001841
- A self-generating sequence: every positive integer occurs as a(i)-a(j) for a unique pair i,j.at n=15A001856
- Shuffling 2n cards.at n=40A002139
- q-expansion of modular form of weight 13/2: eta(8 tau)^12 * theta(tau).at n=45A002284
- q-expansion of modular form of weight 13/2: eta(8 tau)^12 * theta(tau).at n=72A002284
- Numbers that are the sum of 10 positive 6th powers.at n=15A003366
- Degrees of irreducible representations of Mathieu group M_23.at n=13A003858
- Degrees of irreducible representations of Mathieu group M_23.at n=14A003858
- Degrees of irreducible representations of Mathieu group M_24.at n=12A003859
- Degrees of irreducible representations of Mathieu group M_24.at n=11A003859
- Degrees of irreducible representations of alternating group A_11.at n=24A003866
- Degrees of irreducible representations of alternating group A_11.at n=23A003866
- Degrees of irreducible representations of symmetric group S_11.at n=39A003875