Properties of the Number 21154

Twenty-One Thousand One Hundred Fifty-Four

Basics

Value: 21153 → 21154 → 21155

Parity: even

Prime: No

Previous Prime: 21149

Next Prime: 21157

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 2 × 7 × 1511

Divisors: 1, 2, 7, 14, 1511, 3022, 10577, 21154

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101001010100010

Octal: 51242

Duodecimal: 102AA

Hexadecimal: 52a2

Square: 447491716

Square Root: 145.44414735560864

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

Coefficients in the power series A(x) such that: 1 = ∑_n=-oo..+oo x^2·n+1 * (1 - xⁿ)ⁿ⁺¹ * A(x)ⁿ. A356783

Numbers k such that σ(k) = σ(k+11). A15881

Least integer b>2n+1 such that the numbers written as [1,3,...,2n-1,2n+1] and [2n+1,2n-1,...,3,1] in base b are both prime. A218465

Numbers that are the sum of four fourth powers in exactly two ways. A344193

Triangle T, read by rows, such that the matrix inverse satisfies: [T^-1](n,k) = -(k+1)*T(n-1,0) for n>k>=0, with T(n,n)=1 for n>=0. A112911

Column 1 of triangle A112911. A112912

a(n) = ∑_k=1..n sigma₂(k) * floor(n/k). A356042

Partition the j digits of n into blocks of k, with 1 <= k <= j-1, starting at left and multiply. Sum of these numbers equals n. A275171

a(n) = Bell(n) + n - 2 (cf. A000110). A338735

Number of nX4 0..1 arrays with every element unequal to 0, 2, 3, 4 or 7 king-move adjacent elements, with upper left element zero. A304890