Properties of the Number 9981

Nine Thousand Nine Hundred Eighty-One

Basics

Value: 9980 → 9981 → 9982

Parity: odd

Prime: No

Previous Prime: 9973

Next Prime: 10007

Digit Sum: 27

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 1109

Divisors: 1, 3, 9, 1109, 3327, 9981

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 10011011111101

Octal: 23375

Duodecimal: 5939

Hexadecimal: 26fd

Square: 99620361

Square Root: 99.90495483208028

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: No

Perfect Number: No

Special

Kaprekar Constant: No

Munchausen Constant: No

Armstrong Number: No

Kaprekar Number: No

Catalan Number: No

Vampire Number: No

Taxicab Number: No

Super Prime: No

Friedman Number: No

Fermat Number: No

Cullen Number: No

OEIS Sequences

a(n) = floor(n*φ¹²), where φ is the golden ratio, A001622. A4927

Numbers without comma-successors: these are the numbers k such that if the commas sequence A121805 is started at k instead of 1, there is no second term. A367341

Number of Dyck paths of semilength n having no ascents of length 2 that start at an odd level. A114465

Triangle read by rows: T(n,k) is the number of Dyck paths of semilength n having k ascents of length 2 starting at an odd level (0<=k<=floor(n/2)-1 for n>=2; k=0 for n=0,1). A114463

G.f. is the cube of the g.f. of A006950. A273226

Number of odd singletons in all partitions of n (n>=0). A265257

Odd numbers for which σ(k) is congruent to 2 modulo 4 and the 3-adic valuation of k is one larger than the 3-adic valuation of σ(k). A351534

Table read by antidiagonals: Place k points in general position on each side of a regular n-gon and join every pair of the n*(k+1) boundary points by a chord; T(n,k) (n >= 3, k >= 0) gives number of vertices in the resulting planar graph. A367183

Berend Jan van der Zwaag's conjectured complete list of numbers that start different "expanding periodic loops" under the mapping described in A053392 and A060630. A103117

Numbers n such that n+2, n+4, n+6, n+8, n+10, n+12 and n+14 are all semiprimes. A268578