21,212
21,212 is a composite number, even.
21,212 (twenty-one thousand two hundred twelve) is an even 5-digit number. It is a composite number with 6 divisors, and factors as 2² × 5,303. Its digits read the same forwards and backwards, so it is a palindromic number. Written other ways, in hexadecimal, 0x52DC.
Interestingness
Properties
- Parity
- Even
- Digit count
- 5
- Digit sum
- 8
- Digit product
- 8
- Digital root
- 8
- Palindrome
- Yes
- Bit width
- 15 bits
- Recamán's sequence
- a(41,415) = 21,212
- Square (n²)
- 449,948,944
- Cube (n³)
- 9,544,317,000,128
- Divisor count
- 6
- σ(n) — sum of divisors
- 37,128
- φ(n) — Euler's totient
- 10,604
- Sum of prime factors
- 5,307
Primality
Prime factorization: 2 2 × 5303
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√21,212 = [145; (1, 1, 1, 4, 9, 5, 2, 35, 1, 21, 2, 3, 3, 2, 2, 72, 2, 2, 3, 3, 2, 21, 1, 35, …)]
Period length 32 — the block in parentheses repeats forever.
Representations
- In words
- twenty-one thousand two hundred twelve
- Ordinal
- 21212th
- Binary
- 101001011011100
- Octal
- 51334
- Hexadecimal
- 0x52DC
- Base64
- Utw=
- One's complement
- 44,323 (16-bit)
- Scientific notation
- 2.1212 × 10⁴
- As a duration
- 21,212 s = 5 hours, 53 minutes, 32 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒌋𒁹𒁹𒁹 𒌋𒌋𒌋𒁹𒁹
- Egyptian hieroglyphic
- 𓂍𓂍𓆼𓍢𓍢𓎆𓏺𓏺
- Greek (Milesian)
- ͵κασιβʹ
- Mayan (base 20)
- 𝋢·𝋭·𝋠·𝋬
- Chinese
- 二萬一千二百一十二
- Chinese (financial)
- 貳萬壹仟貳佰壹拾貳
Digit at this position in famous constants
- π — Pi (π)
- Digit 21,212 = 1
- e — Euler's number (e)
- Digit 21,212 = 3
- φ — Golden ratio (φ)
- Digit 21,212 = 4
- √2 — Pythagoras's (√2)
- Digit 21,212 = 1
- ln 2 — Natural log of 2
- Digit 21,212 = 0
- γ — Euler-Mascheroni (γ)
- Digit 21,212 = 5
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 21212, here are decompositions:
- 19 + 21193 = 21212
- 43 + 21169 = 21212
- 73 + 21139 = 21212
- 151 + 21061 = 21212
- 181 + 21031 = 21212
- 193 + 21019 = 21212
- 199 + 21013 = 21212
- 211 + 21001 = 21212
Showing the first eight; more decompositions exist.
UTF-8 encoding: E5 8B 9C (3 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.82.220.
- Address
- 0.0.82.220
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.82.220
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 21212 first appears in π at position 208,157 of the decimal expansion (the 208,157ordinal-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
- Mayan numerals — Vigesimal dots-and-bars with a shell zero — one of the earliest true zeros.