690
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 1728
- Proper Divisor Sum (Aliquot Sum)
- 1038
- 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
- 176
- Möbius Function
- 1
- Radical
- 690
- Omega Function (Ω)
- 4
- 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
- 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
- 126
- Smith Number
- yes
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
- yes
- Odd
- no
Names
- German
- sechshundertneunzig· ordinal: sechshundertneunzigste
- English
- six hundred ninety· ordinal: six hundred ninetieth
- Spanish
- seiscientos noventa· ordinal: 690º
- French
- six cent quatre-vingt-dix· ordinal: six cent quatre-vingt-dixième
- Italian
- seicentonovanta· ordinal: 690º
- Latin
- sescenti nonaginta· ordinal: 690.
- Portuguese
- seiscentos e noventa· ordinal: 690º
Appears in sequences
- Number of compositions of n into 3 ordered relatively prime parts.at n=43A000741
- a(n) = a(n-1)*a(n-2) + 1, a(0) = 1, a(1) = 3.at n=5A001056
- Smallest even number that is an unordered sum of two odd primes in exactly n ways.at n=39A001172
- a(0) = 1, a(1) = 4; thereafter a(n)*(2n + 10) - a(n-1)*(11n + 35) + a(n-2)*(8n + 2) + a(n-3)*(15n + 7) + a(n-4)*(4n - 2) = 0.at n=5A001559
- Numbers in which every digit contains at least one loop (version 1).at n=28A001743
- Numbers dividing A002037(i) and larger than A002037(i-1), for some i>0.at n=56A002038
- Denominators of Bernoulli numbers B_{2n}.at n=22A002445
- Number of planar 2-trees with n nodes.at n=4A003093
- Numbers that are the sum of 5 positive 4th powers.at n=45A003339
- Numbers that are the sum of 6 positive 4th powers.at n=54A003340
- Number of partitions of n of the form a_1*b_1^2 + a_2*b_2^2 + ...; number of semisimple rings with p^n elements for any prime p.at n=18A004101
- Josephus problem: numbers m such that, when m people are arranged on a circle and numbered 1 through m, the final survivor when we remove every 4th person is one of the first three people.at n=17A005427
- Number of n-step self-avoiding walks on f.c.c. lattice from (0,0,0) to (2,2,2).at n=2A005548
- Numbers k such that k^16 + 1 is prime.at n=32A006313
- Triangular numbers plus quarter squares: n*(n+1)/2 + floor(n^2/4) (i.e., A000217(n) + A002620(n)).at n=30A006578
- Smith (or joke) numbers: composite numbers k such that sum of digits of k = sum of digits of prime factors of k (counted with multiplicity).at n=34A006753
- Denominators of Bernoulli numbers B_0, B_1, B_2, B_4, B_6, ...at n=23A006954
- Denominator of (2n+1) B_{2n}, where B_n are the Bernoulli numbers.at n=44A006955
- Expansion of (1+x^2)/((1-x)^2*(1-x^3)).at n=44A007980
- Coordination sequence T2 for Zeolite Code AFR.at n=20A008020