Number

121

121 is a composite number, odd, a calendar year.

Consecutive Digits Deficient Number Gapful Number Odious Number Palindrome Perfect Square Pernicious Number Powerful Number Recamán's Sequence Self Number Semiprime Smith Number Year

Historical context — 121 AD

Calendar year

Year 121 (CXXI) was a common year starting on Tuesday of the Julian calendar.

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Historical context — 121 BC

Calendar year

Year 121 BC was a year of the pre-Julian Roman 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: Wednesday
January 1, 121
Ended on: Wednesday
December 31, 121
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 120s
120–129
Century: 2nd century
101–200
Millennium: 1st millennium
1–1000
Years ago: 1,905
1905 years before 2026.

In other calendars

Hebrew: 3881 / 3882 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Metal zodiac:Rooster
Sexagenary cycle position 58 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 664 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 113 / 114 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 43 / 42 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 4
Digit product: 2
Digital root: 4
Palindrome: Yes
Bit width: 7 bits
Recamán's sequence: a(158) = 121
Square (n²): 14,641
Cube (n³): 1,771,561
Square root (√n): 11
Divisor count: 3
σ(n) — sum of divisors: 133
φ(n) — Euler's totient: 110
Sum of prime factors: 22

Primality

Prime factorization: 11 ²

Nearest primes: 113 (−8) · 127 (+6)

Divisors & multiples

All divisors (3)

1 · 11 · 121

Aliquot sum (sum of proper divisors): 12

Factor pairs (a × b = 121)

1 × 121

11 × 11

First multiples

121 · 242 (double) · 363 · 484 · 605 · 726 · 847 · 968 · 1,089 · 1,210

Sums & aliquot sequence

As a sum of two squares: 0² + 11²

As consecutive integers: 60 + 61 6 + 7 + … + 16

Aliquot sequence: 121 → 12 → 16 → 15 → 9 → 4 → 3 → 1 → 0 — terminates at zero

Representations

In words: one hundred twenty-one
Ordinal: 121st
Roman numeral: CXXI
Binary: 1111001
Octal: 171
Hexadecimal: 0x79
Base64: eQ==
One's complement: 134 (8-bit)

In other bases

ternary (3) 11111

quaternary (4) 1321

quinary (5) 441

senary (6) 321

septenary (7) 232

nonary (9) 144

undecimal (11) 100

duodecimal (12) a1

tridecimal (13) 94

tetradecimal (14) 89

pentadecimal (15) 81

Historical numeral systems

Babylonian (base 60): 𒁹𒁹 𒁹
Egyptian hieroglyphic: 𓍢𓎆𓎆𓏺
Greek (Milesian): ρκαʹ
Mayan (base 20): 𝋦·𝋡
Chinese: 一百二十一
Chinese (financial): 壹佰貳拾壹

In other modern scripts

Eastern Arabic ١٢١ Devanagari १२१ Bengali ১২১ Tamil ௧௨௧ Thai ๑๒๑ Tibetan ༡༢༡ Khmer ១២១ Lao ໑໒໑ Burmese ၁၂၁

Digit at this position in famous constants

π — Pi (π): Digit 121 = 7
e — Euler's number (e): Digit 121 = 1
φ — Golden ratio (φ): Digit 121 = 2
√2 — Pythagoras's (√2): Digit 121 = 4
ln 2 — Natural log of 2: Digit 121 = 3
γ — Euler-Mascheroni (γ): Digit 121 = 0

Also seen as

ASCII character

As an ASCII codepoint, 121 is y. Printable ASCII character y.

Hex color

#000079

RGB(0, 0, 121)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.121.

Address: 0.0.0.121
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.121

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