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Properties of the Number 21693

Twenty-One Thousand Six Hundred Ninety-Three

Basics

Value: 21692 → 21693 → 21694

Parity: odd

Prime: No

Previous Prime: 21683

Next Prime: 21701

Digit Sum: 21

Digital Root: 3

Palindrome: No

Factorization: 3 × 7 × 1033

Divisors: 1, 3, 7, 21, 1033, 3099, 7231, 21693

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

2196 Try Today's Challenge

Representations

Binary: 101010010111101

Octal: 52275

Duodecimal: 10679

Hexadecimal: 54bd

Square: 470586249

Square Root: 147.28543716199508

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

Numbers m such that 2m reversed is prime. A57708
T(n,k)=Number of (n+1)X(k+1) 0..2 arrays with 2X2 edge jumps all no more than +1 in one of the clockwise or counterclockwise directions or both. A235223
Number of partitions p of n such that the number of parts is a part and max(p) - min(p) is not a part. A241384
a(n) = Re(b(n)) where b(n)=(1+i)*b(n-1)+b(n-2), with b(1)=0, b(2)=1. A143056
Integer log of (numerator of convergent to E / denominator of convergent to E) = A001414(A007676/A007677) = A001414(A007676)-A001414(A007677). A136122
Triangle read by rows: T(n, k) = C(n, k)*C(2·k, k)/(k+1) - sum(j = 0..k, (-1)j*(1-j)n*C(k, j)/k!), 0<=k<=n. A247493
Number of (n+1) X (1+1) 0..2 arrays with 2 X 2 edge jumps all no more than +1 in one of the clockwise or counterclockwise directions or both. A235216
Number of (n+1)X(4+1) 0..2 arrays with 2X2 edge jumps all no more than +1 in one of the clockwise or counterclockwise directions or both. A235219
a(n) = a(1)*a(n-1) + a(2)*a(n-2) + ... + a(n-3)*a(3) for n >= 4, with initial terms 1, 3, 1, 1. A25255
Smallest number which requires n iterations to reach a prime when iterating x + sum of squares of digits of x. A94658