Number

840

840 is a composite number, even, a calendar year.

Abundant Number Harshad / Niven Year

Properties

Parity: Even
Digit count: 3
Digit sum: 12
Digital root: 3
Palindrome: No
Divisor count: 32
σ(n) — sum of divisors: 2,880

Primality

Prime factorization: 2 ³ × 3 × 5 × 7

Divisors & multiples

All divisors (32)

1 · 2 · 3 · 4 · 5 · 6 · 7 · 8 · 10 · 12 · 14 · 15 · 20 · 21 · 24 · 28 · 30 · 35 · 40 · 42 · 56 · 60 · 70 · 84 · 105 · 120 · 140 · 168 · 210 · 280 · 420 · 840

Aliquot sum (sum of proper divisors): 2,040

Factor pairs (a × b = 840)

1 × 840

2 × 420

3 × 280

4 × 210

5 × 168

6 × 140

7 × 120

8 × 105

10 × 84

12 × 70

14 × 60

15 × 56

20 × 42

21 × 40

24 × 35

28 × 30

First multiples

840 · 1,680 · 2,520 · 3,360 · 4,200 · 5,040 · 5,880 · 6,720 · 7,560 · 8,400

Representations

In words: eight hundred forty
Ordinal: 840th
Roman numeral: DCCCXL
Binary: 1101001000
Octal: 1510
Hexadecimal: 348

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 840, here are decompositions:

11 + 829 = 840
13 + 827 = 840
17 + 823 = 840
19 + 821 = 840
29 + 811 = 840
31 + 809 = 840
43 + 797 = 840
53 + 787 = 840

Showing the first eight; more decompositions exist.

Unicode codepoint

U+0348

Non-spacing mark (Mn)

UTF-8 encoding: CD 88 (2 bytes).

Lookup U+0348 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#000348

RGB(0, 3, 72)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.3.72.