Properties of the Number 2780

Two Thousand Seven Hundred Eighty

Basics

Value: 2779 → 2780 → 2781

Parity: even

Prime: No

Previous Prime: 2777

Next Prime: 2789

Digit Sum: 17

Digital Root: 8

Palindrome: No

Factorization: 2 ² × 5 × 139

Divisors: 1, 2, 4, 5, 10, 20, 139, 278, 556, 695

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101011011100

Octal: 5334

Duodecimal: 1738

Hexadecimal: adc

Square: 7728400

Square Root: 52.72570530585627

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

Mian-Chowla sequence (a B₂ sequence): a(1) = 1; for n>1, a(n) = smallest number > a(n-1) such that the pairwise sums of elements are all distinct. A5282

a(n) = ∑_{k = 1..n} (n - k + 1)^k. A3101

Numbers n such that the decimal expansions of both n and n² have 0 as smallest digit and 8 as largest digit. A256708

The partition function G(n,3). A1680

Years in which there are five Fridays in the month of February. A141287

Integer part of decimal 'base-2 looking' numbers divided by their actual base-2 values (denominator of a(n) is n, numerator is n written in binary but read in decimal). A32532

Numbers m such that there are precisely 11 groups of order m. A249554

Number G(n,k) of set partitions of {1,...,n} into sets of size at most k; triangle G(n,k), n>=0, 0<=k<=n, read by rows. A229223

Number T(n,k) of set partitions of [n] such that the maximal absolute difference between the least elements of consecutive blocks equals k; triangle T(n,k), n>=0, 0<=k<=max(n-1,0), read by rows. A287215

a(n) = n*(3·n + 19)/2. A140675