12,721
12,721 is a prime, odd.
12,721 (twelve thousand seven hundred twenty-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, 0x31B1.
Interestingness
Properties
- Parity
- Odd
- Digit count
- 5
- Digit sum
- 13
- Digit product
- 28
- Digital root
- 4
- Palindrome
- Yes
- Bit width
- 14 bits
- Recamán's sequence
- a(48,833) = 12,721
- Square (n²)
- 161,823,841
- Cube (n³)
- 2,058,561,081,361
- Divisor count
- 2
- σ(n) — sum of divisors
- 12,722
- φ(n) — Euler's totient
- 12,720
Primality
12,721 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√12,721 = [112; (1, 3, 1, 2, 2, 1, 1, 1, 6, 4, 1, 6, 4, 9, 6, 2, 1, 31, 1, 1, 5, 1, 1, 2, …)]
Representations
- In words
- twelve thousand seven hundred twenty-one
- Ordinal
- 12721st
- Binary
- 11000110110001
- Octal
- 30661
- Hexadecimal
- 0x31B1
- Base64
- MbE=
- One's complement
- 52,814 (16-bit)
- Scientific notation
- 1.2721 × 10⁴
- As a duration
- 12,721 s = 3 hours, 32 minutes, 1 second
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹 𒌋𒌋𒌋𒁹𒁹 𒁹
- Egyptian hieroglyphic
- 𓂍𓆼𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓏺
- Greek (Milesian)
- ͵ιβψκαʹ
- Mayan (base 20)
- 𝋡·𝋫·𝋰·𝋡
- Chinese
- 一萬二千七百二十一
- Chinese (financial)
- 壹萬貳仟柒佰貳拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 12,721 = 1
- e — Euler's number (e)
- Digit 12,721 = 1
- φ — Golden ratio (φ)
- Digit 12,721 = 0
- √2 — Pythagoras's (√2)
- Digit 12,721 = 2
- ln 2 — Natural log of 2
- Digit 12,721 = 9
- γ — Euler-Mascheroni (γ)
- Digit 12,721 = 9
Also seen as
UTF-8 encoding: E3 86 B1 (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.49.177.
- Address
- 0.0.49.177
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.49.177
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Heard as a frequency, 12,721 Hz is closest to:
- Concert pitch (A4 = 440 Hz): G9 (12543.9 Hz, +24¢)
- Scientific pitch (C4 = 256 Hz): G♯9 (13004 Hz, -38¢)
- Baroque pitch (A4 = 415 Hz): G♯9 (12534.7 Hz, +26¢)
The digit sequence 12721 first appears in π at position 54,516 of the decimal expansion (the 54,516ordinal-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.
- Egyptian hieroglyphic numerals — Seven hieroglyphs for every power of ten, from a single stroke to a million.