Properties of the Number 19661

Nineteen Thousand Six Hundred Sixty-One

Basics

Value: 19660 → 19661 → 19662

Parity: odd

Prime: Yes

Previous Prime: 19609

Next Prime: 19681

Digit Sum: 23

Digital Root: 5

Palindrome: No

Factorization: 19661

Divisors: 1, 19661

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 100110011001101

Octal: 46315

Duodecimal: B465

Hexadecimal: 4ccd

Square: 386554921

Square Root: 140.21768789992225

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

Record gaps between primes (upper end) (compare A002386, which gives lower ends of these gaps). A101

Prime islands: for n >= 2, a(n) = least prime whose adjacent primes are exactly 2n apart; a(1) = 3 by convention. A46931

Smallest prime p such that there is a gap of 2n between p and previous prime. A1632

Expansion of 1/(1+x-2·x³). A77973

Numbers k such that A003313(k) = A003313(5·k). A116460

Number of permutations of {1,2,...,n} with no increasing cycles of length >=2. A cycle (b(1), b(2), ...) is said to be increasing if, when written with its smallest element in the first position, it satisfies b(1)<b(2)<b(3)<... . A186758

Primes having only {1, 6, 9} as digits. A363023

a(n) = 3·a(n-1) + 4·a(n-2), a(0)=1, a(1)=5. A108981

Triangle read by rows: T(n,k) is the number of permutations of {1,2,...,n} having k increasing cycles of length >=2 (0<=k<= n/2). A cycle (b(1), b(2), ...) is said to be increasing if, when written with its smallest element in the first position, it satisfies b(1) < b(2) < b(3) < ... . A186757

Primes that are the first in a run of exactly 4 emirps. A346024