Properties of the Number 11991

Eleven Thousand Nine Hundred Ninety-One

Basics

Value: 11990 → 11991 → 11992

Parity: odd

Prime: No

Previous Prime: 11987

Next Prime: 12007

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 3 × 7 × 571

Divisors: 1, 3, 7, 21, 571, 1713, 3997, 11991

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 10111011010111

Octal: 27327

Duodecimal: 6B33

Hexadecimal: 2ed7

Square: 143784081

Square Root: 109.50342460398214

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

Numbers whose square in base 2 is a palindrome. A3166

Triangle of numbers a(n,k), 0 <= k <= n: number of set partitions of {1,2,...,n} in which exactly k of the blocks have been distinguished. A49020

a(n) = p² + p + 1 where p runs through the primes. A60800

Numbers k such that σ(k) = σ(k+6). A15866

Descending dungeons: a(10)=10; for n>10, a(n) = a(n-1) read as if it were written in base n. A121265

Array read by descending antidiagonals: A(n,k) is the number of oriented colorings of the facets of a regular n-dimensional orthotope using up to k colors. A325004

Number of oriented colorings of the 8 cubic facets of a tesseract or of the 8 vertices of a hyperoctahedron. A337956

Square array T(n,k), n >= 0, k >= 0, read by antidiagonals, where T(n,k) is ∑_i=0..n binomial(n,i)*∑_j=0..i binomial(i,j)^k. A328807

Numbers of the form 110 + p². (where p is a prime). A138693

G.f.: ∑_n>=0 exp(-(1 + n²*x)) * (1 + n²*x)ⁿ / n!. A245109