Properties of the Number 21541

Twenty-One Thousand Five Hundred Forty-One

Basics

Value: 21540 → 21541 → 21542

Parity: odd

Prime: No

Previous Prime: 21529

Next Prime: 21557

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 13 × 1657

Divisors: 1, 13, 1657, 21541

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 101010000100101

Octal: 52045

Duodecimal: 10571

Hexadecimal: 5425

Square: 464014681

Square Root: 146.76852523616907

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

a(n) = 13·a(n-1) - 65·a(n-2) + 156·a(n-3) - 182·a(n-4) + 91·a(n-5) - 13·a(n-6), with initial terms 0, -1, -5, -22, -91, -364. A216597

Numbers whose sum of divisors equals the sum of their anti-divisors. A178029

a(1) = 3; a(n) = smallest number such that the forward as well as the reverse n-th partial concatenation is a prime for n>1. A83993

Numbers whose sum of their anti-divisors divides the sum of their divisors. A191581

Number of partitions of n+5 with largest inscribed rectangle having area <= n. A218626

Numbers n such that the sum of the distinct prime factors of prime(n)-1 and prime(n+1)-1 are the same. A259562

Number of partitions satisfying (cn(2,5) = cn(3,5) and cn(0,5) <= cn(1,5) and cn(0,5) <= cn(4,5)). A36805

Numbers whose sum of anti-divisors is equal to the sum of its unitary divisors. A273992

a(n) = 13·a(n-1) - 65·a(n-2) + 156·a(n-3) - 182·a(n-4) + 91·a(n-5) - 13·a(n-6), with initial terms 6, 13, 39, 130, 455, 1638. A216508

Addends k > 0 such that x² + k produces a new minimum of its Hardy-Littlewood Constant. A331949