Number

8,161

8,161 is a prime, odd.

8,161 (eight thousand one hundred sixty-one) is an odd 4-digit number. It is a prime number — divisible only by 1 and itself. Written other ways, in hexadecimal, 0x1FE1.

Arithmetic Number Cube-Free Deficient Number Flippable Odious Number Prime Pythagorean Prime Recamán's Sequence Sexy Prime Squarefree

Interestingness

★ ★ ★ ★ ★

8 notable facts · grade A

8,149 8,150 8,151 8,152 8,153 8,154 8,155 8,156 8,157 8,158 8,159 8,160 8,161 8,162 8,163 8,164 8,165 8,166 8,167 8,168 8,169 8,170 8,171 8,172 8,173

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Properties

Parity: Odd
Digit count: 4
Digit sum: 16
Digit product: 48
Digital root: 7
Palindrome: No
Bit width: 13 bits
Reversed: 1,618
Flips to (rotate 180°): 1,918
Recamán's sequence: a(10,445) = 8,161
Square (n²): 66,601,921
Cube (n³): 543,538,277,281
Divisor count: 2
σ(n) — sum of divisors: 8,162
φ(n) — Euler's totient: 8,160

Primality

8,161 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)

1 · 8161

Aliquot sum (sum of proper divisors): 1

Factor pairs (a × b = 8,161)

1 × 8161

First multiples

8,161 · 16,322 (double) · 24,483 · 32,644 · 40,805 · 48,966 · 57,127 · 65,288 · 73,449 · 81,610

Sums & aliquot sequence

As a sum of two squares: 40² + 81²

As consecutive integers: 4,080 + 4,081

Continued fraction of √n

√8,161 = [90; (2, 1, 21, 1, 11, 11, 4, 1, 3, 1, 4, 1, 5, 1, 6, 2, 1, 2, 10, 3, 1, 11, 3, 2, …)]

Representations

In words: eight thousand one hundred sixty-one
Ordinal: 8161st
Binary: 1111111100001
Octal: 17741
Hexadecimal: 0x1FE1
Base64: H+E=
One's complement: 57,374 (16-bit)
Scientific notation: 8.161 × 10³
As a duration: 8,161 s = 2 hours, 16 minutes, 1 second

In other bases

ternary (3) 102012021

quaternary (4) 1333201

quinary (5) 230121

senary (6) 101441

septenary (7) 32536

nonary (9) 12167

undecimal (11) 614a

duodecimal (12) 4881

tridecimal (13) 393a

tetradecimal (14) 2d8d

pentadecimal (15) 2641

As an angle

8,161° = 22 × 360° + 241°

241° ≈ 4.206 rad

Compass bearing: WSW (west-southwest)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒁹𒁹 𒌋𒁹𒁹𒁹𒁹𒁹𒁹 𒁹
Egyptian hieroglyphic: 𓆼𓆼𓆼𓆼𓆼𓆼𓆼𓆼𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓏺
Greek (Milesian): ͵ηρξαʹ
Mayan (base 20): 𝋡·𝋠·𝋨·𝋡
Chinese: 八千一百六十一
Chinese (financial): 捌仟壹佰陸拾壹

In other modern scripts

Eastern Arabic ٨١٦١ Devanagari ८१६१ Bengali ৮১৬১ Tamil ௮௧௬௧ Thai ๘๑๖๑ Tibetan ༨༡༦༡ Khmer ៨១៦១ Lao ໘໑໖໑ Burmese ၈၁၆၁

Digit at this position in famous constants

π — Pi (π): Digit 8,161 = 1
e — Euler's number (e): Digit 8,161 = 2
φ — Golden ratio (φ): Digit 8,161 = 7
√2 — Pythagoras's (√2): Digit 8,161 = 3
ln 2 — Natural log of 2: Digit 8,161 = 5
γ — Euler-Mascheroni (γ): Digit 8,161 = 4

Also seen as

Prime neighborhood

Adjacent primes:

Previous prime: 8,147 (gap of 14)
Next prime: 8,167 (gap of 6)

Pair status: sexy with 8167.

Unicode codepoint

ῡ

Greek Small Letter Upsilon With Macron

U+1FE1

Lowercase letter (Ll)

UTF-8 encoding: E1 BF A1 (3 bytes).

Lookup U+1FE1 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#001FE1

RGB(0, 31, 225)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.31.225.

Address: 0.0.31.225
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.31.225

Unspecified address (0.0.0.0/8) — "this network" placeholder.

Musical pitch

Heard as a frequency, 8,161 Hz is closest to:

Concert pitch (A4 = 440 Hz): C9 (8372 Hz, -44¢)
Scientific pitch (C4 = 256 Hz): C9 (8192 Hz, -7¢)
Baroque pitch (A4 = 415 Hz): C♯9 (8365.9 Hz, -43¢)

Position in π

The digit sequence 8161 first appears in π at position 1,650 of the decimal expansion (the 1,650ordinal-suffix:th digit after the integer 3).

Search range: the first 1,000,000 fractional digits of π. Any 6-digit-or-shorter string is virtually guaranteed to appear in there — the more interesting signal is the position.

Look up 8161 on Pi Search ↗