Properties of the Number 18981

Eighteen Thousand Nine Hundred Eighty-One

Basics

Value: 18980 → 18981 → 18982

Parity: odd

Prime: No

Previous Prime: 18979

Next Prime: 19001

Digit Sum: 27

Digital Root: 9

Palindrome: Yes

Factorization: 3 ³ × 19 × 37

Divisors: 1, 3, 9, 19, 27, 37, 57, 111, 171, 333

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 100101000100101

Octal: 45045

Duodecimal: AB99

Hexadecimal: 4a25

Square: 360278361

Square Root: 137.77155003846042

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) = n*(2·n+5)*(n-1)/6. A51925

q-factorial numbers 3!_q. A69778

T(n,k)=Number of nXk 0..3 arrays with no more than floor(nXk/2) elements unequal to at least one horizontal or antidiagonal neighbor, with new values introduced in row major 0..3 order. A222906

Palindromic and divisible by 9. A45644

Consider all (2n+1)-digit palindromic primes of the form 10...0M0...01 (so that M is a palindrome with <= 2n-1 digits); a(n) = smallest such M. A100026

Palindromic nonagonal (or 9-gonal or enneagonal) numbers. A82723

Palindromes with exactly 5 prime factors (counted with multiplicity). A46331

Numbers n such that φ(n) = φ(n+12) and n is not divisible by 2. A217141

Cubeful (i.e., not cubefree) palindromes. A35133

Palindromes divisible by their digit sum. A82232