Properties of the Number -780

Seven Hundred Eighty

Basics

Value: -781 → -780 → -779

Parity: even

Prime: No

Previous Prime:

Next Prime: 1

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

Today's Target

8509 Try Today's Challenge

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

a(n) = ∑_d∣n (-1)^d-1*d². A321543

Alternating sum of squares to n. A89594

Riordan array (1/(1+4x+x²), x/(1+4x+x²)). A159764

McKay-Thompson series of class 12I for the Monster group. A58487

a(0) = 1, a(1) = -4, a(n) = -4·a(n-1) - a(n-2) for n > 1. A125905

Expansion of q^-1/2 * (η(q) * η(q²))⁴ in powers of q. A30211

Expansion of (1-x-x^N)/((1-x)(1-x²)(1-x³)...(1-x^N)) for N = 10. A60029

a(n) = -A001353(n). A106707

Triangle T(n, k, m) = t(n, m)/(t(k, m)*t(n-k, m)), where t(n, k) = ∏_j=1..n p(j, k+1), p(n, x) = ∑_j=0..n (-1)^j*A053122(n, j)*x^j, and m = 5, read by rows. A156599

A Seidel matrix A(n,k) read by antidiagonals upwards. A323833