399
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 640
- Proper Divisor Sum (Aliquot Sum)
- 241
- 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
- 216
- Möbius Function
- -1
- Radical
- 399
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 120
- Smith Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- dreihundertneunundneunzig· ordinal: dreihundertneunundneunzigste
- English
- three hundred ninety-nine· ordinal: three hundred ninety-ninth
- Spanish
- trescientos noventa y nueve· ordinal: 399º
- French
- trois cent quatre-vingt-dix-neuf· ordinal: trois cent quatre-vingt-dix-neufième
- Italian
- trecentonovantanove· ordinal: 399º
- Latin
- trecenti nonaginta novem· ordinal: 399.
- Portuguese
- trezentos e noventa e nove· ordinal: 399º
Appears in sequences
- Number of rooted simplicial 3-polytopes with n+3 nodes; or rooted 3-connected triangulations with 2n+2 faces; or rooted 3-connected trivalent maps with 2n+2 vertices.at n=5A000260
- a(n) = 4*n^2 - 1.at n=10A000466
- Flavius Josephus's sieve: Start with the natural numbers; at the k-th sieving step, remove every (k+1)-st term of the sequence remaining after the (k-1)-st sieving step; iterate.at n=22A000960
- Number of sublattices of index n in generic 3-dimensional lattice.at n=13A001001
- Moran numbers: k such that k/(sum of digits of k) is prime.at n=30A001101
- Denominators of cosecant numbers: -2*(2^(2*n-1)-1)*Bernoulli(2*n).at n=27A001897
- Denominators of cosecant numbers: -2*(2^(2*n-1)-1)*Bernoulli(2*n).at n=9A001897
- Numbers dividing A002037(i) and larger than A002037(i-1), for some i>0.at n=36A002038
- Numbers y such that p^2 = x^2 + y^2, 0 < x < y, p = A002144(n).at n=37A002365
- Odd squarefree numbers with an odd number of prime factors that have no prime factors greater than 31.at n=20A002556
- Numbers k such that (k^2 + k + 1)/13 is prime.at n=20A002642
- Numbers k such that (k^2 + 1)/2 is prime.at n=60A002731
- Continued fraction for Euler's constant (or Euler-Mascheroni constant) gamma.at n=39A002852
- Numbers k such that k! + 1 is prime.at n=14A002981
- Smallest multiple of n whose digits sum to n.at n=21A002998
- Dimensions of split simple Lie algebras over any field of characteristic zero.at n=44A003038
- Schur's 1926 partition theorem: number of partitions of n into parts 6n+1 or 6n-1.at n=49A003105
- a(n+1) = 1 + a( floor(n/1) ) + a( floor(n/2) ) + ... + a( floor(n/n) ).at n=16A003318
- Divisors of 2^18 - 1.at n=14A003528
- Divisors of 2^36 - 1.at n=40A003543