Properties of the Number 20690

Twenty Thousand Six Hundred Ninety

Basics

Value: 20689 → 20690 → 20691

Parity: even

Prime: No

Previous Prime: 20681

Next Prime: 20693

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 2 × 5 × 2069

Divisors: 1, 2, 5, 10, 2069, 4138, 10345, 20690

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101000011010010

Octal: 50322

Duodecimal: BB82

Hexadecimal: 50d2

Square: 428076100

Square Root: 143.8401890988746

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 integer partitions of n with unimodal run-lengths. A332280

T(n,k)=Number of nXk 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4. A241435

a(n) = ∑_k=0..n binomial(n,k) * binomial((k+1)², n). A346183

Number of nX4 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of elements above it or zero plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4. A241431

Number of (n+1) X (5+1) 0..1 arrays with every 2 X 2 subblock antidiagonal maximum minus diagonal minimum nondecreasing horizontally and diagonal maximum minus antidiagonal minimum nondecreasing vertically. A253394

Number of binary strings of length n avoiding 4-antipowers. A275061

a(n) = ∑_i=0..n T(i,n-i), array T as in A048149. A49712

Antidiagonal triangular matrices of factorials as the example: M(3)={{0, 0, 1}, {0, 1, 2}, {1, 2, 6}}; the matrices are used to get characteristic polynomials and the triangular sequence is the coefficients of those characteristic polynomials. A137296

Number of 7Xn 0..3 arrays with no element equal to one plus the sum of elements to its left or one plus the sum of the elements above it or zero plus the sum of the elements diagonally to its northwest or one plus the sum of the elements antidiagonally to its northeast, modulo 4. A241441

Numbers of form 7 x² + 8 y². A20690