647
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 648
- 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
- 646
- Möbius Function
- -1
- Radical
- 647
- 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
- 38
- 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
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 118
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Names
- German
- sechshundertsiebenundvierzig· ordinal: sechshundertsiebenundvierzigste
- English
- six hundred forty-seven· ordinal: six hundred forty-seventh
- Spanish
- seiscientos cuarenta y siete· ordinal: 647º
- French
- six cent quarante-sept· ordinal: six cent quarante-septième
- Italian
- seicentoquarantasette· ordinal: 647º
- Latin
- sescenti quadraginta septem· ordinal: 647.
- Portuguese
- seiscentos e quarenta e sete· ordinal: 647º
Appears in sequences
- Primes that divide at least one term in every Fibonacci sequence.at n=26A000057
- Numbers that are not the sum of 4 tetrahedral numbers.at n=35A000797
- 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=40A000928
- Primes with 5 as smallest primitive root.at n=16A001124
- Full reptend primes: primes with primitive root 10.at n=42A001913
- Prime determinants of forms with class number 2.at n=55A002052
- Smallest prime == 7 (mod 8) where Q(sqrt(-p)) has class number 2n+1.at n=11A002146
- Squares written in base 9.at n=22A002442
- Number of integral points in a certain sequence of closed quadrilaterals.at n=37A002579
- Number of unrooted achiral trees with n nodes.at n=19A003244
- Numbers that are the sum of 8 positive 5th powers.at n=22A003353
- Numbers that are the sum of 12 positive 7th powers.at n=5A003379
- Number of solid partitions of n supported on graph of cube.at n=13A003404
- a(n) = floor((n^2 + 6n - 3)/4).at n=47A004116
- Divisible only by primes congruent to 3 mod 7.at n=39A004621
- Divisible only by primes congruent to 7 mod 8.at n=38A004628
- Class 1+ primes: primes of the form 2^i*3^j - 1 with i, j >= 0.at n=16A005105
- Class 2- primes (for definition see A005109).at n=52A005110
- States of a dynamic storage system.at n=9A005594
- Numbers k such that k-6, k, and k+6 are primes.at n=23A006489