Properties of the Number 21321

Twenty-One Thousand Three Hundred Twenty-One

Basics

Value: 21320 → 21321 → 21322

Parity: odd

Prime: No

Previous Prime: 21319

Next Prime: 21323

Digit Sum: 9

Digital Root: 9

Palindrome: No

Factorization: 3 ² × 23 × 103

Divisors: 1, 3, 9, 23, 69, 103, 207, 309, 927, 2369

Polygonal

Triangular: Yes

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001101001001

Octal: 51511

Duodecimal: 10409

Hexadecimal: 5349

Square: 454585041

Square Root: 146.01712228365548

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

Partial sums of A299266. A299267

a(n) = ∑_k=1..n gcd(k, n)³. A343497

Partial sums of sequence (essentially A002378): 1, 2, 6, 12, 20, 30, 42, 56, 72, 90, ... A64999

a(n) = coefficient of xⁿ in A(x) such that: 1 = ∑_n=-oo..+oo xⁿ * (A(x) - x^6·n+5)^n-1. A358965

Numbers divisible by the sum of 5th powers of their digits. A169666

Unique representation of nonnegative numbers by iterated tribonacci A, B and C sequences. A316713

Triangular numbers t which are average of two consecutive primes p and p+4. A129752

"DHK" (bracelet, identity, unlabeled) transform of 2,2,2,2,... A32251

Denominators of continued fraction convergents to sqrt(549). A42051

a(1) = 1; a(n) is the smallest triangular number > a(n-1) which differs from it at every digit. A68855