Properties of the Number 21505

Twenty-One Thousand Five Hundred Five

Basics

Value: 21504 → 21505 → 21506

Parity: odd

Prime: No

Previous Prime: 21503

Next Prime: 21517

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 5 × 11 × 17 × 23

Divisors: 1, 5, 11, 17, 23, 55, 85, 115, 187, 253

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010000000001

Octal: 52001

Duodecimal: 10541

Hexadecimal: 5401

Square: 462465025

Square Root: 146.64583185348297

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

Sextuple factorials, 6-factorials, n!!!!!!, n!6. A85158

Sextuple factorial numbers: ∏_k=0..n-1 (6·k + 5). A8543

4-dimensional analog of centered polygonal numbers: a(n) = n(n+1)*(n²+n+4)/12. A6007

a(n) = ∑_d∣n (2^n-d). A74854

Odd octagonal numbers: (2n+1)*(6n+1). A14641

Infinite square array read by antidiagonals downwards: T(0,m) = prime(m), m >= 1; for n >= 1, T(n,m) = T(n-1,m)*T(n-1,m+1)/gcd(T(n-1,m), T(n-1,m+1))², m >= 1. A255483

Triangle read by rows, the inverse Bell transform of n!*binomial(5,n) (without column 0). A13988

A partition product of Stirling₂ type [parameter k = 5] with biggest-part statistic (triangle read by rows). A157405

a(n) = (4·n³ + n² - 3·n)/2. A172073

a(1)=10; if n = Product p_i^e_i, n > 1, then a(n) = Product p_i+1^e_i·Product p_i+3^e_i. A45973