# 65 (number)

65
65 (sixty-five) is the natural number following 64 and preceding 66.wikipedia
61 Related Articles

### 66 (number)

66Sixty Six
65 (sixty-five) is the natural number following 64 and preceding 66.
66 (sixty-six) is the natural number following 65 and preceding 67.

### 64 (number)

64sixty-four
65 (sixty-five) is the natural number following 64 and preceding 66.
64 (sixty-four) is the natural number following 63 and preceding 65.

### Octagonal number

Octagonal
It is an octagonal number.
1, 8, 21, 40, 65, 96, 133, 176, 225, 280, 341, 408, 481, 560, 645, 736, 833, 936

### Natural number

natural numberspositive integerpositive integers
65 (sixty-five) is the natural number following 64 and preceding 66.

### Semiprime

biprimesemiprimessemiprime number
Sixty-five is the 23rd semiprime and the 3rd of the form (5.q).

### Cullen number

Cullen primeCullen
It is also a Cullen number.

### Mertens function

M''(12)
Given 65, the Mertens function returns 0.

### 0

zerozero function0 (number)
Given 65, the Mertens function returns 0.

### Magic constant

magic sum
This number is the magic constant of 5 by 5 normal magic square: This number is also the magic constant of n-Queens Problem for n = 5.

### Magic square

magic squaressimple magic squaresimple magic squares
This number is the magic constant of 5 by 5 normal magic square:

### Eight queens puzzle

n''-queens problemn-Queens Problemn queens problem
This number is also the magic constant of n-Queens Problem for n = 5.

It appears in the Padovan sequence, preceded by the terms 28, 37, 49 (it is the sum of the first two of these).

### Idoneal number

Euler's idoneal numbers
There are only 65 known Euler's idoneal numbers.

### Pythagorean triple

Pythagorean triplesPythagorean triangleEuclid's formula
65 is the length of the hypotenuse of 4 different Pythagorean triangles, the lowest number to have more than 2: 65 2 = 16 2 + 63 2 = 33 2 + 56 2 = 39 2 + 52 2 = 25 2 + 60 2.

### Atomic number

proton numberZatomic numbers
*The atomic number of terbium, a lanthanide

### Terbium

TbTerbium (III)
*The atomic number of terbium, a lanthanide

### Messier object

MessierMessier CatalogueList of Messier objects

M653623

### Galaxy

galaxiesgalacticgalactic nuclei

### Apparent magnitude

apparent visual magnitudemagnitudevisual magnitude

### Constellation

constellationsEuropean constellationModern constellation

### Leo (constellation)

LeoLeoneLeo constellation

### New General Catalogue

NGCICIndex Catalogue

### Spiral galaxy

spiral galaxiesspiral armspiral

### Cetus

Cetus (constellation)CetWhale