Properties of the Number 21768

Twenty-One Thousand Seven Hundred Sixty-Eight

Basics

Value: 21767 → 21768 → 21769

Parity: even

Prime: No

Previous Prime: 21767

Next Prime: 21773

Digit Sum: 24

Digital Root: 6

Palindrome: No

Factorization: 2 ³ × 3 × 907

Divisors: 1, 2, 3, 4, 6, 8, 12, 24, 907, 1814

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010100001000

Octal: 52410

Duodecimal: 10720

Hexadecimal: 5508

Square: 473845824

Square Root: 147.53982513206392

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 inequivalent binary [ n,3 ] codes of dimension <= 3 without zero columns. A34337

Solutions·to the negative Pell equation y² = 72·x² - 1331712 with x,y >= 0. A281241

a(n) = ∑_1<=i<=j<=n prime(i)*prime(j). A357251

Absolute value of second differences of A005849. A128194

Number of 0..n arrays x(0..9) of 10 elements with zero 6th differences. A200333

Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 430", based on the 5-celled von Neumann neighborhood. A272116

Numbers k such that k·2^k/2 + 1 is prime. A58767

a(n) = 2^n-1 * ∑_k=0..n ((n+k)!/(n-k)!)/k!. A72331

Array read by ascending antidiagonals: A(n, k) = (-1)^{n + k} * ∑_j=0..k j! * Stirling1(n, j) * Stirling1(k, j). A379820

Concatenate sum and product of decimal digits of n. A380873