Properties of the Number 21073

Twenty-One Thousand Seventy-Three

Basics

Value: 21072 → 21073 → 21074

Parity: odd

Prime: No

Previous Prime: 21067

Next Prime: 21089

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 13 × 1621

Divisors: 1, 13, 1621, 21073

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001001010001

Octal: 51121

Duodecimal: 10241

Hexadecimal: 5251

Square: 444071329

Square Root: 145.16542288024377

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

T(n,k)=Number of (n+2)X(k+2) 0..1 arrays with every 3X3 subblock sum of the two medians of the central row and column plus the two sums of the diagonal and antidiagonal nondecreasing horizontally, vertically and ne-to-sw antidiagonally. A259006

Number of unlabeled connected series-parallel posets with n nodes. A7453

G.f.: (1 + x⁴ + x⁵ + x⁶ + x¹⁰ + x¹¹ + x¹² + x¹⁶)/∏_i=1..8 (1 - xⁱ). A256975

a(n) = ∑_{k=0..floor(n/5)} binomial(n,5·k)*binomial(6·k,k)/(5·k+1). A226910

a(1) = 1; thereafter a(n) is always the smallest integer > a(n-1) not leading to a contradiction, such that any five consecutive digits in the sequence sum up to a prime. A152605

Numbers missing from A001033 despite satisfying the necessary congruence conditions (see comments). A274470

Strong pseudoprimes to base 89. A20315

Number of (n+2)X(2+2) 0..1 arrays with every 3X3 subblock sum of the two medians of the central row and column plus the two sums of the diagonal and antidiagonal nondecreasing horizontally, vertically and ne-to-sw antidiagonally. A259000

Number of (3+2)X(n+2) 0..1 arrays with every 3X3 subblock sum of the two medians of the central row and column plus the two sums of the diagonal and antidiagonal nondecreasing horizontally, vertically and ne-to-sw antidiagonally. A259008

Number of base 21 circular n-digit numbers with adjacent digits differing by 1 or less. A124714