Properties of the Number 18781

Eighteen Thousand Seven Hundred Eighty-One

Basics

Value: 18780 → 18781 → 18782

Parity: odd

Prime: No

Previous Prime: 18773

Next Prime: 18787

Digit Sum: 25

Digital Root: 7

Palindrome: Yes

Factorization: 7 × 2683

Divisors: 1, 7, 2683, 18781

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 100100101011101

Octal: 44535

Duodecimal: AA51

Hexadecimal: 495d

Square: 352725961

Square Root: 137.04378862246912

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 rucksack partitions of n: every consecutive constant subsequence has a different sum. A353864

Number of integer partitions of n whose rounded-down mean is 2. A363745

Sums of 5 distinct powers of 5. A38477

Palindromes arising in A053779. A53780

a(n) = A051707(A025487). A108460

Palindromic primes in base 9 (written in base 9). A117703

a(n) = ∑_k=0..n (-1)^k * binomial(n+k,n-k) * Fibonacci(k+1). A390851

Palindromes with successive increasing difference: a(k)-a(k-1) > a(k+1)- a(k). A71250

a(1) = 1, then the rearrangement of odd palindromes such that every concatenation is a prime for n > 1. A113578

Least positive integer m > 1 such that 1 - m^k + m^2k - m^3k + m^4k is prime, where k = A003592(n). A181980