Properties of the Number 1221

One Thousand Two Hundred Twenty-One

Basics

Value: 1220 → 1221 → 1222

Parity: odd

Prime: No

Previous Prime: 1217

Next Prime: 1223

Digit Sum: 6

Digital Root: 6

Palindrome: Yes

Factorization: 3 × 11 × 37

Divisors: 1, 3, 11, 33, 37, 111, 407, 1221

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 10011000101

Octal: 2305

Duodecimal: 859

Hexadecimal: 4c5

Square: 1490841

Square Root: 34.942810419312295

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

Integers written in factorial base. A7623

n written in primorial base. A49345

Numbers that contain only 1's and 2's. Nonempty binary strings of length n in lexicographic order. A7931

a(n) = n² - 4. A28347

Numerator of 1/4 - 1/n². A61037

a(n) = ∑_k=1..n n/gcd(n,k). A57660

Triangle read by rows of achiral color patterns (set partitions) for a row or loop of length n. T(n,k) is the number using exactly k colors (sets). A304972

Palindromic in bases 5 and 10. A29962

Fourth spoke of a hexagonal spiral. A56108

Numbers whose sum of digits is 6. A52220