Properties of the Number 21879

Twenty-One Thousand Eight Hundred Seventy-Nine

Basics

Value: 21878 → 21879 → 21880

Parity: odd

Prime: No

Previous Prime: 21871

Next Prime: 21881

Digit Sum: 27

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 11 × 13 × 17

Divisors: 1, 3, 9, 11, 13, 17, 33, 39, 51, 99

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010101110111

Octal: 52567

Duodecimal: 107B3

Hexadecimal: 5577

Square: 478690641

Square Root: 147.9155164274526

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

Number of sets (in the Hausdorff metric geometry) at each location between two sets defining a polygonal configuration consisting of two 4-gonal polygonal components chained with string components of length l as l varies. A152929

a(n) = n*(n+1)*(n+2)*(n+3)*(n+4)*(2 + 4·n + n²)/840. A101097

Largest order of a permutation of n elements with exactly 4 cycles. Also the largest LCM of a 4-partition of n. A129649

Number of n-bead bracelets (turnover necklaces) with 8 red beads and n-8 black beads. A5514

Odd numbers k such that k divides A005940(k). A364545

Triangle read by rows: numerators of the almost-Riordan array ( (1 - x + sqrt(1 - 2·x))/(1 - 2·x + (1 - x)*sqrt(1 - 2·x)) | 2/(1 - 2·x + (1 - x)*sqrt(1 - 2·x)), 2*(1 - x - sqrt(1 - 2·x))/x ). A389708

Product of terms in row n of A082817. A82820

Row sums of A095167. A95170

a(n) = n*(n + 1)*(7·n + 5)/6. A304993

Irregular triangle T(n,k) read by rows of the reduced coefficients of π^2·k in the expansion of ∑_k>=1 (1 / (4·k²-1)ⁿ). A382782