16931
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 2
- Divisor Sum
- 16932
- Proper Divisor Sum (Aliquot Sum)
- 1
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 16930
- Möbius Function
- -1
- Radical
- 16931
- 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
- 84
- Smith Number
- no
- Vampire 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
- yes
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Prime Index
- 1953
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- no
- Odd
- yes
Appears in sequences
- Smallest prime p==3 (mod 8) such that Q(sqrt(-p)) has class number 2n+1.at n=34A002148
- Primes that remain prime through 3 iterations of function f(x) = 2x + 9.at n=34A023276
- Numerators of continued fraction convergents to sqrt(350).at n=7A041662
- a(1) = 2; a(n) is the smallest prime > a(n-1) such that a(n) + a(n-1) is a square.at n=17A062064
- If a,b are prime numbers satisfying the Diophantine equation a^3+b^3=c^2, then a is -1 mod 12 and b is 1 mod 12, or vice versa. Choose 'a' to be -1 mod 12. This is the sequence of 'a' values, sorted by the magnitude of c.at n=7A099806
- Primes congruent to 24 mod 53.at n=31A142554
- Primes congruent to 57 mod 59.at n=32A142784
- Primes congruent to 34 mod 61.at n=29A142832
- Values of p in A145767.at n=8A145797
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, 0, 1), (0, 0, 1), (1, -1, 1), (1, 1, -1), (1, 1, 1)}.at n=7A150899
- A three-dimensional version of the cellular automaton A160118, using cubes.at n=21A160119
- Primes of the form 2*k^2 + 3.at n=19A201473
- Primes of the form 8n^2 + 3.at n=10A201611
- Primes p such that if q is the next prime after p then the concatenation of p with q and the concatenation of q with p are both primes.at n=31A225575
- Primes of the form n^2 + pi(n).at n=22A228865
- (2,3,5,7)-primes (see comments for precise definition).at n=19A262728
- Primes p such that A272207(p) = p.at n=19A276030
- Primes of the form k!8+2, where k!8 is the octuple factorial number (A114800).at n=8A288716
- Number of nX7 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 0, 2 or 4 neighboring 1s.at n=2A297693
- T(n,k)=Number of nXk 0..1 arrays with every 1 horizontally, diagonally or antidiagonally adjacent to 0, 2 or 4 neighboring 1s.at n=38A297694