Properties of the Number 19991

Nineteen Thousand Nine Hundred Ninety-One

Basics

Value: 19990 → 19991 → 19992

Parity: odd

Prime: Yes

Previous Prime: 19979

Next Prime: 19993

Digit Sum: 29

Digital Root: 2

Palindrome: Yes

Factorization: 19991

Divisors: 1, 19991

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 100111000010111

Octal: 47027

Duodecimal: B69B

Hexadecimal: 4e17

Square: 399640081

Square Root: 141.38953285162236

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

Palindromic primes: prime numbers whose decimal expansion is a palindrome. A2385

Primes having only {1, 2, 9} as digits. A385776

Primes having only {0, 1, 9} as digits. A199329

Primes with either no internal digits or all internal digits are 9. A69684

Primes that contain digits 1 and 9 only. A20457

Primes having only {1, 4, 9} as digits. A260271

Primes at which the difference pattern X24Y (X and Y >= 6) occurs in A001223. A52163

Smallest palindromic prime containing exactly n 9's. A83980

G.f. satisfies: A(x) = 1/(1 - x/A(-x·A(x)⁶)²). A213228

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