Properties of the Number 780

Seven Hundred Eighty

Basics

Value: 779 → 780 → 781

Parity: even

Prime: No

Previous Prime: 773

Next Prime: 787

Digit Sum: 15

Digital Root: 6

Palindrome: No

Factorization: 2 ² × 3 × 5 × 13

Divisors: 1, 2, 3, 4, 5, 6, 10, 12, 13, 15

Polygonal

Triangular: Yes

Square: No

Pentagonal: No

Hexagonal: Yes

Heptagonal: No

Tetrahedral: No

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Representations

Binary: 1100001100

Octal: 1414

Duodecimal: 550

Hexadecimal: 30c

Square: 608400

Square Root: 27.92848008753788

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

Triangular numbers: a(n) = binomial(n+1,2) = n*(n+1)/2 = 0 + 1 + 2 + ... + n. A217

Hexagonal numbers: a(n) = n*(2·n-1). A384

Total number of parts in all partitions of n. Also, sum of largest parts of all partitions of n. A6128

a(n) = 4·a(n-1) - a(n-2) with a(0) = 0, a(1) = 1. A1353

Number of n-step self-avoiding walks on square lattice. A1411

a(n) = n² - 4. A28347

a(n) = binomial(n,2): number of size-2 subsets of {0,1,...,n} that contain no consecutive integers. A161680

a(n) = 4·a(n-2) - a(n-4) for n > 1, a(n) = n for n = 0, 1. A2530

a(n) = ∑_d∣n (-1)^d-1*d². A321543

Numbers k such that 3^k - 2 is prime. A14224