Properties of the Number 680

Six Hundred Eighty

Basics

Value: 679 → 680 → 681

Parity: even

Prime: No

Previous Prime: 677

Next Prime: 683

Digit Sum: 14

Digital Root: 5

Palindrome: No

Factorization: 2 ³ × 5 × 17

Divisors: 1, 2, 4, 5, 8, 10, 17, 20, 34, 40

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: Yes

Today's Target

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Representations

Binary: 1010101000

Octal: 1250

Duodecimal: 488

Hexadecimal: 2a8

Square: 462400

Square Root: 26.076809620810597

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

Tetrahedral (or triangular pyramidal) numbers: a(n) = C(n+2,3) = n*(n+1)*(n+2)/6. A292

Triangle read by rows: T(n,k) is the number of compositions of n into nonzero parts with k parts directly followed by a different part, n>=0, 0<=k<=A004523(n-1). A238279

Triangle read by rows: T(n,k) is the number of compositions into nonzero parts with k parts directly followed by a different part, n>=0, 0<=k<=n. A238130

Numbers that are products of 5 primes (or 5-almost primes, a generalization of semiprimes). A14614

a(n) = 1² + 3² + 5² + 7² + ... + (2·n-1)² = n*(4·n² - 1)/3. A447

Triangle read by rows: T(n, k) = binomial(n + k, 2·k). A85478

Monotonic ordering of set S generated by these rules: if·and y are in S then x² + y² is in S, and 1 is in S. A192476

Numbers of edges of regular polygons constructible with ruler (or, more precisely, an unmarked straightedge) and compass. A3401

Numbers k such that k⁸ + 1 is prime. A6314

Numbers that are the sum of 10 positive 5th powers. A3355