Properties of the Number 21565

Twenty-One Thousand Five Hundred Sixty-Five

Basics

Value: 21564 → 21565 → 21566

Parity: odd

Prime: No

Previous Prime: 21563

Next Prime: 21569

Digit Sum: 19

Digital Root: 1

Palindrome: No

Factorization: 5 × 19 × 227

Divisors: 1, 5, 19, 95, 227, 1135, 4313, 21565

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

8509 Try Today's Challenge

Representations

Binary: 101010000111101

Octal: 52075

Duodecimal: 10591

Hexadecimal: 543d

Square: 465049225

Square Root: 146.85026387446499

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 strict compositions of n with alternating parts strictly decreasing. A342343

Antidiagonal sums of triangle A123610. A123612

Numerators of increasingly better rational approximations to log(3)/log(2) with increasing denominators. A254351

Numerators of fractions converging to limiting value of Fekete polynomials. A280034

Number of series-reduced rooted trees whose leaves are integer partitions whose multiset union is an integer partition of n with no 1's. A320293

Number of partitions of 4n whose xor-sum is 2n. A370874

1/3 the number of n X n 0..2 symmetric matrices with every element equal to two, three or four horizontal and vertical neighbors. A211050

Numbers k > 1 such that (3/2)^k sets a new record for closest fractional part to 1/2. A334264

Denominators of fractions converging to limiting value of Fekete polynomials. A280035

Base-10 numbers k whose number of divisors equals the number of divisors in R(k), where k is written in all bases from base-2 to base-10 and R(k), the digit reversal of k, is read as a number in the same base. A346113