9,991
9,991 is a composite number, odd.
Properties
- Parity
- Odd
- Digit count
- 4
- Digit sum
- 28
- Digit product
- 729
- Digital root
- 1
- Palindrome
- No
- Bit width
- 14 bits
- Reversed
- 1,999
- Flips to (rotate 180°)
- 1,666
- Recamán's sequence
- a(7,233) = 9,991
- Square (n²)
- 99,820,081
- Cube (n³)
- 997,302,429,271
- Divisor count
- 4
- σ(n) — sum of divisors
- 10,192
- φ(n) — Euler's totient
- 9,792
- Sum of prime factors
- 200
Primality
Prime factorization: 97 × 103
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- nine thousand nine hundred ninety-one
- Ordinal
- 9991st
- Binary
- 10011100000111
- Octal
- 23407
- Hexadecimal
- 0x2707
- Base64
- Jwc=
- One's complement
- 55,544 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹 𒌋𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒁹
- Egyptian hieroglyphic
- 𓆼𓆼𓆼𓆼𓆼𓆼𓆼𓆼𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ͵θϡϟαʹ
- Mayan (base 20)
- 𝋡·𝋤·𝋳·𝋫
- Chinese
- 九千九百九十一
- Chinese (financial)
- 玖仟玖佰玖拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 9,991 = 5
- e — Euler's number (e)
- Digit 9,991 = 7
- φ — Golden ratio (φ)
- Digit 9,991 = 2
- √2 — Pythagoras's (√2)
- Digit 9,991 = 8
- ln 2 — Natural log of 2
- Digit 9,991 = 0
- γ — Euler-Mascheroni (γ)
- Digit 9,991 = 8
Also seen as
UTF-8 encoding: E2 9C 87 (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.39.7.
- Address
- 0.0.39.7
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.39.7
Unspecified address (0.0.0.0/8) — "this network" placeholder.
This passes the ABA routing number checksum and matches the Federal Reserve numbering scheme.
Banks operate many routing numbers per state and division; an unmatched checksum-valid number can still be a real RTN at a smaller institution.
The digit sequence 9991 first appears in π at position 17,561 of the decimal expansion (the 17,561ordinal-suffix:st 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.