21,157
21,157 is a prime, odd.
21,157 (twenty-one thousand one hundred fifty-seven) is an odd 5-digit number. It is a prime number — divisible only by 1 and itself. Written other ways, in hexadecimal, 0x52A5.
Interestingness
Properties
- Parity
- Odd
- Digit count
- 5
- Digit sum
- 16
- Digit product
- 70
- Digital root
- 7
- Palindrome
- No
- Bit width
- 15 bits
- Reversed
- 75,112
- Recamán's sequence
- a(41,525) = 21,157
- Square (n²)
- 447,618,649
- Cube (n³)
- 9,470,267,756,893
- Divisor count
- 2
- σ(n) — sum of divisors
- 21,158
- φ(n) — Euler's totient
- 21,156
Primality
21,157 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√21,157 = [145; (2, 4, 1, 96, 6, 1, 1, 1, 1, 31, 1, 2, 1, 1, 6, 1, 1, 10, 4, 5, 2, 5, 1, 2, …)]
Representations
- In words
- twenty-one thousand one hundred fifty-seven
- Ordinal
- 21157th
- Binary
- 101001010100101
- Octal
- 51245
- Hexadecimal
- 0x52A5
- Base64
- UqU=
- One's complement
- 44,378 (16-bit)
- Scientific notation
- 2.1157 × 10⁴
- As a duration
- 21,157 s = 5 hours, 52 minutes, 37 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋𒁹𒁹 𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓍢𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ͵καρνζʹ
- Mayan (base 20)
- 𝋢·𝋬·𝋱·𝋱
- Chinese
- 二萬一千一百五十七
- Chinese (financial)
- 貳萬壹仟壹佰伍拾柒
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,157 = 0
- e — Euler's number (e)
- Digit 21,157 = 9
- φ — Golden ratio (φ)
- Digit 21,157 = 6
- √2 — Pythagoras's (√2)
- Digit 21,157 = 3
- ln 2 — Natural log of 2
- Digit 21,157 = 1
- γ — Euler-Mascheroni (γ)
- Digit 21,157 = 6
Also seen as
UTF-8 encoding: E5 8A A5 (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.82.165.
- Address
- 0.0.82.165
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.82.165
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 21157 first appears in π at position 17,398 of the decimal expansion (the 17,398ordinal-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.