Number

15,661

15,661 is a prime, odd.

Arithmetic Number Deficient Number Emirp Odious Number Prime Pythagorean Prime Recamán's Sequence Sexy Prime Squarefree

Properties

Parity: Odd
Digit count: 5
Digit sum: 19
Digit product: 180
Digital root: 1
Palindrome: No
Bit width: 14 bits
Reversed: 16,651
Recamán's sequence: a(18,810) = 15,661
Square (n²): 245,266,921
Cube (n³): 3,841,125,249,781
Divisor count: 2
σ(n) — sum of divisors: 15,662
φ(n) — Euler's totient: 15,660

Primality

15,661 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)

1 · 15661

Aliquot sum (sum of proper divisors): 1

Factor pairs (a × b = 15,661)

1 × 15661

First multiples

15,661 · 31,322 (double) · 46,983 · 62,644 · 78,305 · 93,966 · 109,627 · 125,288 · 140,949 · 156,610

Sums & aliquot sequence

As a sum of two squares: 6² + 125²

As consecutive integers: 7,830 + 7,831

Representations

In words: fifteen thousand six hundred sixty-one
Ordinal: 15661st
Binary: 11110100101101
Octal: 36455
Hexadecimal: 0x3D2D
Base64: PS0=
One's complement: 49,874 (16-bit)

In other bases

ternary (3) 210111001

quaternary (4) 3310231

quinary (5) 1000121

senary (6) 200301

septenary (7) 63442

nonary (9) 23431

undecimal (11) 10848

duodecimal (12) 9091

tridecimal (13) 7189

tetradecimal (14) 59c9

pentadecimal (15) 4991

Historical numeral systems

Babylonian (base 60): 𒁹𒁹𒁹𒁹 𒌋𒌋𒁹 𒁹
Egyptian hieroglyphic: 𓂍𓆼𓆼𓆼𓆼𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓏺
Greek (Milesian): ͵ιεχξαʹ
Mayan (base 20): 𝋡·𝋳·𝋣·𝋡
Chinese: 一萬五千六百六十一
Chinese (financial): 壹萬伍仟陸佰陸拾壹

In other modern scripts

Eastern Arabic ١٥٦٦١ Devanagari १५६६१ Bengali ১৫৬৬১ Tamil ௧௫௬௬௧ Thai ๑๕๖๖๑ Tibetan ༡༥༦༦༡ Khmer ១៥៦៦១ Lao ໑໕໖໖໑ Burmese ၁၅၆၆၁

Digit at this position in famous constants

π — Pi (π): Digit 15,661 = 9
e — Euler's number (e): Digit 15,661 = 4
φ — Golden ratio (φ): Digit 15,661 = 1
√2 — Pythagoras's (√2): Digit 15,661 = 8
ln 2 — Natural log of 2: Digit 15,661 = 4
γ — Euler-Mascheroni (γ): Digit 15,661 = 7

Also seen as

Prime neighborhood

Adjacent primes:

Previous prime: 15,649 (gap of 12)
Next prime: 15,667 (gap of 6)

Pair status: sexy with 15667.

Unicode codepoint

㴭

CJK Unified Ideograph-3D2D

U+3D2D

Other letter (Lo)

UTF-8 encoding: E3 B4 AD (3 bytes).

Lookup U+3D2D on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#003D2D

RGB(0, 61, 45)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.61.45.

Address: 0.0.61.45
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.61.45

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

Position in π

The digit sequence 15661 first appears in π at position 16,648 of the decimal expansion (the 16,648ordinal-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 15661 on Pi Search ↗