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Properties of the Number 21640

Twenty-One Thousand Six Hundred Forty

Basics

Value: 21639 → 21640 → 21641

Parity: even

Prime: No

Previous Prime: 21617

Next Prime: 21647

Digit Sum: 13

Digital Root: 4

Palindrome: No

Factorization: 2 3 × 5 × 541

Divisors: 1, 2, 4, 5, 8, 10, 20, 40, 541, 1082

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010010001000

Octal: 52210

Duodecimal: 10634

Hexadecimal: 5488

Square: 468289600

Square Root: 147.10540438746634

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

Number of integer compositions of n that are not the first sums of any finite nonnegative sequence. A391645
Number of compositions (ordered partitions) of n into octagonal numbers (A000567). A322800
Number of upward triangles in a Star of David matchstick arrangement of size n. A45950
Number of (n+1) X (6+1) 0..1 arrays with no 2 X 2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements. A251126
Numbers k such that Bernoulli number Bk has denominator 13530. A295587
Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 73. A31571
First occurrence of n consecutive n's in the decimal expansion of sqrt(3). A224874
T(n,k)=Number of (n+1)X(k+1) 0..1 arrays with no 2X2 subblock having the sum of its diagonal elements greater than the maximum of its antidiagonal elements. A251128
Values of Euler's totient φ for A050498. A339883
Number of (3+1) X (n+1) 0..1 arrays with each row divisible by 3 and column not divisible by 3, read as a binary number with top and left being the most significant bits. A262422