Properties of the Number 1661

One Thousand Six Hundred Sixty-One

Basics

Value: 1660 → 1661 → 1662

Parity: odd

Prime: No

Previous Prime: 1657

Next Prime: 1663

Digit Sum: 14

Digital Root: 5

Palindrome: Yes

Factorization: 11 × 151

Divisors: 1, 11, 151, 1661

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 11001111101

Octal: 3175

Duodecimal: B65

Hexadecimal: 67d

Square: 2758921

Square Root: 40.755367744629666

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

Triangle read by rows: T(n,k) = ∑_j>=0 j!*T(n-j-1, k-1) for n >= 0, k >= 0. A84938

Number of balanced partitions of n: the largest part equals the number of parts. A47993

Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 25 (most significant digit on right). A61978

Number of partitions of n in which the sequence of frequencies of the summands is nondecreasing. A100883

Write 1,2,... in a clockwise spiral; sequence gives numbers on positive·axis. A33951

Number of integer partitions of n that are empty, (1), or have at least two parts and these parts are pairwise coprime. A327516

a(n) = a(n-1) + a(n-2) + a(n-3), with a(0) = 1, a(1) = a(2) = 3. A214825

a(1)=1, a(n)=a(n-1)+n if n odd, a(n)=a(n-1)+ n² if n is even. A140113

a(n) = 2·a(n-1) - 2·a(n-3) + a(n-4) for n > 3, with initial terms 1, 1, 4, 8. A267682

Numbers all of whose divisors are palindromic. A62687