Properties of the Number 21218

Twenty-One Thousand Two Hundred Eighteen

Basics

Value: 21217 → 21218 → 21219

Parity: even

Prime: No

Previous Prime: 21211

Next Prime: 21221

Digit Sum: 14

Digital Root: 5

Palindrome: No

Factorization: 2 × 103 ²

Divisors: 1, 2, 103, 206, 10609, 21218

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001011100010

Octal: 51342

Duodecimal: 10342

Hexadecimal: 52e2

Square: 450203524

Square Root: 145.6639969244288

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) = 2·prime(n)². A79704

Number of ways to toss a coin n times and not get a run of four. A135491

2·p², for p an odd prime. A143928

Values A such that p=prime(n) satisfies binomial(2p-1, p-1) == 1 + A·p (mod p⁴). A260209

Numbers that are not squarefree and whose Euler totient function is squarefree. A49198

Record high values of A379248. A379294

a(n) = n⁴ + 2⁴ + (n+2)⁴. A190176

Composite numbers k such that ∑_i=1..t-1 d(i+1)/d(i) is prime, where d(1), ..., d(t) are the divisors of k in ascending order. A255585

Number of maximal matchings in the wheel graph on n nodes. A284709

a(n) = - ∑_d∣n (-n/d)^d * binomial(d+n/d-2, d-1). A338688