Properties of the Number 21797

Twenty-One Thousand Seven Hundred Ninety-Seven

Basics

Value: 21796 → 21797 → 21798

Parity: odd

Prime: No

Previous Prime: 21787

Next Prime: 21799

Digit Sum: 26

Digital Root: 8

Palindrome: No

Factorization: 71 × 307

Divisors: 1, 71, 307, 21797

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010100100101

Octal: 52445

Duodecimal: 10745

Hexadecimal: 5525

Square: 475109209

Square Root: 147.63807097087118

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

Composite numbers generated by the Euler polynomial x² + x + 41. A145292

T(n,k) = Number of (n+2) X (k+2) 0..3 arrays with every 3 X 3 subblock row and diagonal sum equal to 1 2 4 6 or 7 and every 3 X 3 column and antidiagonal sum not equal to 1 2 4 6 or 7. A252558

Semiprimes generated by the Euler polynomial x² + x + 41. A228183

MM-numbers of crossing, capturing multiset partitions (with empty parts allowed). A326259

Numerators of the partial alternating sums of the reciprocals of the alternating sum of divisors function (A206369). A379621

Positions of 0's in A330314. A330325

Expansion of (1-x)/(1 - x - x³ - 2·x⁴ + 2·x⁵). A52914

Numbers n such that σ (φ ( n ) ) = σ (σ (n ) ) where φ is Euler's totient and σ is the multiplicative sum-of-divisors function. A65556

a(n) = (2^p - p² - 1)/6 where p = prime(n). A166743

Number of (n+2)X(6+2) 0..3 arrays with every 3X3 subblock row and diagonal sum equal to 1 2 4 6 or 7 and every 3X3 column and antidiagonal sum not equal to 1 2 4 6 or 7. A252556