Properties of the Number 4021

Four Thousand Twenty-One

Basics

Value: 4020 → 4021 → 4022

Parity: odd

Prime: Yes

Previous Prime: 4019

Next Prime: 4027

Digit Sum: 7

Digital Root: 7

Palindrome: No

Factorization: 4021

Divisors: 1, 4021

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 111110110101

Octal: 7665

Duodecimal: 23B1

Hexadecimal: fb5

Square: 16168441

Square Root: 63.41135544995076

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

Primes with first digit 4. A45710

Artiads: the primes p == 1 (mod 5) for which Fibonacci((p-1)/5) is divisible by p. A1583

Number of "ON" cells at n-th stage in simple 2-dimensional cellular automaton (see Comments for precise definition). A160118

Primes congruent to 3 mod 41. A142200

T(n,k)=Number of length n 1..(k+1) arrays with every leading partial sum divisible by 2, 3, 5 or 7. A258631

Irregular triangle T(n,k) read by rows: T(n,k) is the number of compositions of n with k descents, n>=0, 0<=k<=floor(n/3). A238344

a(n) = a(n-1) + a(m) for n >= 4, where m = 2^p+1 + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^p+1, starting with a(1) = a(2) = 1 and a(3) = 2. A50029

Table in which the g.f. of row n, R(n,x), satisfies ∑_k=-oo..+oo (x^k - n·R(n,x))^k = 1 - (n-2)*∑_k>=1 x^k², for n >= 1, as read by antidiagonals. A370030

a(n) = largest prime factor of 7ⁿ-1. A74249

G.f. A(x) satisfies ∑_n=-oo..+oo (xⁿ - 3·A(x))ⁿ = 1 - ∑_n>=1 x^n². A370033