Source: Noto Serif Tangut

U+FF03 Fullwidth Number Sign

U+FF03 was added in Unicode version 1.1 in 1993. It belongs to the block U+FF00 to U+FFEF Halfwidth and Fullwidth Forms in the U+0000 to U+FFFF Basic Multilingual Plane.

This character is a Other Punctuation and is commonly used, that is, in no specific script.

The glyph is a wide version of the glyph Number Sign. Accordingly, its width in East Asian Text is fullwidth. In bidirectional text it is written as end of a European number, e.g., a currency symbol, from left to right. When changing direction it is not mirrored. U+FF03 offers a line break opportunity at its position, except in some numeric contexts.

The Wikipedia has the following information about this codepoint:

The symbol # is known variously in English-speaking regions as the number sign, hash, or pound sign. The symbol has historically been used for a wide range of purposes including the designation of an ordinal number and as a ligatured abbreviation for pounds avoirdupois – having been derived from the now-rare ℔.
Since 2007, widespread usage of the symbol to introduce metadata tags on social media platforms has led to such tags being known as "hashtags", and from that, the symbol itself is sometimes called a hashtag.
The symbol is distinguished from similar symbols by its combination of level horizontal strokes and right-tilting vertical strokes.

Representations

System	Representation
Nº	65283
UTF-8	EF BC 83
UTF-16	FF 03
UTF-32	00 00 FF 03
URL-Quoted	%EF%BC%83
HTML hex reference	＃
Wrong windows-1252 Mojibake	ï¼ƒ
Encoding: EUC-KR (hex bytes)	A3 A3
Encoding: JIS0208 (hex bytes)	A1 F4
Adobe Glyph List	numbersignmonospace

Elsewhere

Complete Record

Property	Value
Age (age)	1.1 (1993)
Unicode Name (na)	FULLWIDTH NUMBER SIGN
Unicode 1 Name (na1)	—
Block (blk)	Halfwidth and Fullwidth Forms
General Category (gc)	Other Punctuation
Script (sc)	Common
Bidirectional Category (bc)	European Terminator
Combining Class (ccc)	Not Reordered
Decomposition Type (dt)	wide
Decomposition Mapping (dm)	Number Sign
Lowercase (Lower)	✘
Simple Lowercase Mapping (slc)	Fullwidth Number Sign
Lowercase Mapping (lc)	Fullwidth Number Sign
Uppercase (Upper)	✘
Simple Uppercase Mapping (suc)	Fullwidth Number Sign
Uppercase Mapping (uc)	Fullwidth Number Sign
Simple Titlecase Mapping (stc)	Fullwidth Number Sign
Titlecase Mapping (tc)	Fullwidth Number Sign
Case Folding (cf)	Fullwidth Number Sign
ASCII Hex Digit (AHex)	✘
Alphabetic (Alpha)	✘
Bidi Control (Bidi_C)	✘
Bidi Mirrored (Bidi_M)	✘
Composition Exclusion (CE)	✘
Case Ignorable (CI)	✘
Changes When Casefolded (CWCF)	✘
Changes When Casemapped (CWCM)	✘
Changes When NFKC Casefolded (CWKCF)	✔
Changes When Lowercased (CWL)	✘
Changes When Titlecased (CWT)	✘
Changes When Uppercased (CWU)	✘
Cased (Cased)	✘
Full Composition Exclusion (Comp_Ex)	✘
Default Ignorable Code Point (DI)	✘
Dash (Dash)	✘
Deprecated (Dep)	✘
Diacritic (Dia)	✘
Emoji Modifier Base (EBase)	✘
Emoji Component (EComp)	✘
Emoji Modifier (EMod)	✘
Emoji Presentation (EPres)	✘
Emoji (Emoji)	✘
Extender (Ext)	✘
Extended Pictographic (ExtPict)	✘
FC NFKC Closure (FC_NFKC)	Fullwidth Number Sign
Grapheme Cluster Break (GCB)	Any
Grapheme Base (Gr_Base)	✔
Grapheme Extend (Gr_Ext)	✘
Grapheme Link (Gr_Link)	✘
Hex Digit (Hex)	✘
Hyphen (Hyphen)	✘
ID Continue (IDC)	✘
ID Start (IDS)	✘
IDS Binary Operator (IDSB)	✘
IDS Trinary Operator and (IDST)	✘
IDSU (IDSU)	0
ID_Compat_Math_Continue (ID_Compat_Math_Continue)	0
ID_Compat_Math_Start (ID_Compat_Math_Start)	0
Ideographic (Ideo)	✘
InCB (InCB)	None
Indic Mantra Category (InMC)	—
Indic Positional Category (InPC)	NA
Indic Syllabic Category (InSC)	Other
Jamo Short Name (JSN)	—
Join Control (Join_C)	✘
Logical Order Exception (LOE)	✘
Math (Math)	✘
Noncharacter Code Point (NChar)	✘
NFC Quick Check (NFC_QC)	Yes
NFD Quick Check (NFD_QC)	Yes
NFKC Casefold (NFKC_CF)	Number Sign
NFKC Quick Check (NFKC_QC)	No
NFKC_SCF (NFKC_SCF)	Number Sign
NFKD Quick Check (NFKD_QC)	No
Other Alphabetic (OAlpha)	✘
Other Default Ignorable Code Point (ODI)	✘
Other Grapheme Extend (OGr_Ext)	✘
Other ID Continue (OIDC)	✘
Other ID Start (OIDS)	✘
Other Lowercase (OLower)	✘
Other Math (OMath)	✘
Other Uppercase (OUpper)	✘
Prepended Concatenation Mark (PCM)	✘
Pattern Syntax (Pat_Syn)	✘
Pattern White Space (Pat_WS)	✘
Quotation Mark (QMark)	✘
Regional Indicator (RI)	✘
Radical (Radical)	✘
Sentence Break (SB)	Other
Soft Dotted (SD)	✘
Sentence Terminal (STerm)	✘
Terminal Punctuation (Term)	✘
Unified Ideograph (UIdeo)	✘
Variation Selector (VS)	✘
Word Break (WB)	Other
White Space (WSpace)	✘
XID Continue (XIDC)	✘
XID Start (XIDS)	✘
Expands On NFC (XO_NFC)	✘
Expands On NFD (XO_NFD)	✘
Expands On NFKC (XO_NFKC)	✘
Expands On NFKD (XO_NFKD)	✘
Bidi Paired Bracket (bpb)	Fullwidth Number Sign
Bidi Paired Bracket Type (bpt)	None
East Asian Width (ea)	fullwidth
Hangul Syllable Type (hst)	Not Applicable
ISO 10646 Comment (isc)	—
Joining Group (jg)	No_Joining_Group
Joining Type (jt)	Non Joining
Line Break (lb)	Ideographic
Numeric Type (nt)	none
Numeric Value (nv)	not a number
Simple Case Folding (scf)	Fullwidth Number Sign
Script Extension (scx)
Vertical Orientation (vo)	U