Properties of the Number 81780

Eighty-One Thousand Seven Hundred Eighty

Basics

Value: 81779 → 81780 → 81781

Parity: even

Prime: No

Previous Prime: 81773

Next Prime: 81799

Digit Sum: 24

Digital Root: 6

Palindrome: No

Factorization: 2 ² × 3 × 5 × 29 × 47

Divisors: 1, 2, 3, 4, 5, 6, 10, 12, 15, 20

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2730 Try Today's Challenge

Representations

Binary: 10011111101110100

Octal: 237564

Duodecimal: 3B3B0

Hexadecimal: 13f74

Square: 6687968400

Square Root: 285.97202660400194

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 compositions of n into nonprime numbers. A52284

The r-th term of the n-th row of the following array contains the sum of r successively decreasing integers beginning from n, 0 < r <= n (see Example). A110426

The fourth row of the ED1 array A167546. A167547

Numbers k such that 4^k + 15 is prime. A253773

a(n) = 108·n² - 104·n + 20 (n>=1). A304835

a(n) = 3·n³ + n² - 4·n. A83127

Number of three-choice polygons by area. A173412

Continued cotangent for square root of 3. A81780