16,661
16,661 is a prime, odd.
16,661 (sixteen thousand six hundred sixty-one) is an odd 5-digit number. It is a prime number — divisible only by 1 and itself. Its digits read the same forwards and backwards, so it is a palindromic number. Written other ways, in hexadecimal, 0x4115.
Interestingness
Properties
Primality
16,661 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√16,661 = [129; (12, 1, 9, 2, 2, 12, 1, 1, 64, 51, 1, 1, 1, 1, 1, 1, 51, 64, 1, 1, 12, 2, 2, 9, …)]
Period length 27 — the block in parentheses repeats forever.
Representations
- In words
- sixteen thousand six hundred sixty-one
- Ordinal
- 16661st
- Binary
- 100000100010101
- Octal
- 40425
- Hexadecimal
- 0x4115
- Base64
- QRU=
- One's complement
- 48,874 (16-bit)
- Scientific notation
- 1.6661 × 10⁴
- As a duration
- 16,661 s = 4 hours, 37 minutes, 41 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒁹
- Egyptian hieroglyphic
- 𓂍𓆼𓆼𓆼𓆼𓆼𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ͵ιϛχξαʹ
- Mayan (base 20)
- 𝋢·𝋡·𝋭·𝋡
- Chinese
- 一萬六千六百六十一
- Chinese (financial)
- 壹萬陸仟陸佰陸拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 16,661 = 4
- e — Euler's number (e)
- Digit 16,661 = 8
- φ — Golden ratio (φ)
- Digit 16,661 = 7
- √2 — Pythagoras's (√2)
- Digit 16,661 = 3
- ln 2 — Natural log of 2
- Digit 16,661 = 7
- γ — Euler-Mascheroni (γ)
- Digit 16,661 = 0
Also seen as
UTF-8 encoding: E4 84 95 (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.65.21.
- Address
- 0.0.65.21
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.65.21
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Heard as a frequency, 16,661 Hz is closest to:
- Concert pitch (A4 = 440 Hz): C10 (16744 Hz, -9¢)
- Scientific pitch (C4 = 256 Hz): C10 (16384 Hz, +29¢)
- Baroque pitch (A4 = 415 Hz): C♯10 (16731.8 Hz, -7¢)
The digit sequence 16661 first appears in π at position 65,195 of the decimal expansion (the 65,195ordinal-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
- Prime numbers — The building blocks of arithmetic: what primes are, why they matter, and how we find them.
- Mayan numerals — Vigesimal dots-and-bars with a shell zero — one of the earliest true zeros.