1,251
1,251 is a composite number, odd, a calendar year.
1,251 (one thousand two hundred fifty-one) is an odd 4-digit number. It is a composite number with 6 divisors, and factors as 3² × 139. Written other ways, in Roman numerals it is MCCLI and in binary, 10011100011.
Interestingness
Historical context — 1251 AD
Calendar year
Year 1251 (MCCLI) was a common year starting on Sunday of the Julian calendar.
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Year facts
- Year type
-
Common year
Standard 365-day year; not divisible by 4 (or divisible by 100 but not 400).
- Days in year
- 365
- ISO weeks
- 52
- Started on
-
Sunday
January 1, 1251
- Ended on
-
Sunday
December 31, 1251
- Friday the 13ths
-
2
2 Friday the 13ths this year.
- Decade
-
1250s
1250–1259
- Century
-
13th century
1201–1300
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
775
775 years before 2026.
In other calendars
- Hebrew
-
5011 / 5012 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
648 / 649 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Pig
Sexagenary cycle position 48 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1794 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
629 / 630 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1243 / 1244 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1173 / 1172 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 3 2 × 139
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√1,251 = [35; (2, 1, 2, 2, 2, 5, 35, 5, 2, 2, 2, 1, 2, 70)]
Period length 14 — the block in parentheses repeats forever.
Representations
- In words
- one thousand two hundred fifty-one
- Ordinal
- 1251st
- Roman numeral
- MCCLI
- Binary
- 10011100011
- Octal
- 2343
- Hexadecimal
- 0x4E3
- Base64
- BOM=
- One's complement
- 64,284 (16-bit)
- Scientific notation
- 1.251 × 10³
- As a duration
- 1,251 s = 20 minutes, 51 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋 𒌋𒌋𒌋𒌋𒌋𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ͵ασναʹ
- Mayan (base 20)
- 𝋣·𝋢·𝋫
- Chinese
- 一千二百五十一
- Chinese (financial)
- 壹仟貳佰伍拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,251 = 4
- e — Euler's number (e)
- Digit 1,251 = 1
- φ — Golden ratio (φ)
- Digit 1,251 = 7
- √2 — Pythagoras's (√2)
- Digit 1,251 = 4
- ln 2 — Natural log of 2
- Digit 1,251 = 0
- γ — Euler-Mascheroni (γ)
- Digit 1,251 = 0
Also seen as
UTF-8 encoding: D3 A3 (2 bytes).
Code page 1251 is Windows-1251 (Cyrillic) — Microsoft Windows encoding for Cyrillic alphabets.
Code pages are integer identifiers used by Windows and other systems to refer to specific character encodings.
As an unsigned 32-bit integer, this is the IPv4 address 0.0.4.227.
- Address
- 0.0.4.227
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.4.227
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Heard as a frequency, 1,251 Hz is closest to:
- Concert pitch (A4 = 440 Hz): D♯6 (1244.5 Hz, +9¢)
- Scientific pitch (C4 = 256 Hz): D♯6 (1217.7 Hz, +47¢ — about midway to E6)
- Baroque pitch (A4 = 415 Hz): E6 (1243.6 Hz, +10¢)
The digit sequence 1251 first appears in π at position 2,498 of the decimal expansion (the 2,498ordinal-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.
Related reading
- Babylonian numerals — The base-60 cuneiform system that gave us 60 minutes, 60 seconds, and 360°.