Mathematical properties
- Integer classification – 881 is an odd natural number that follows 880 and precedes 882.
- Primality – 881 is a prime number; it has no positive divisors other than 1 and itself.
- Twin prime – 881 forms a twin‑prime pair with 883, the next prime number greater than 881.
- Chen prime – Because 881 + 2 = 883 is also prime, 881 qualifies as a Chen prime.
- Prime index – 881 is the 151st prime number.
- Binary representation – In base‑2, 881 is written as 1101110001.
- Octal representation – In base‑8, 881 is 1561₈.
- Hexadecimal representation – In base‑16, 881 is 371₁₆.
- Digit sum – The sum of its decimal digits is 8 + 8 + 1 = 17, which does not divide 881; therefore 881 is not a Harshad (Niven) number.
- Full reptend prime – 10 is a primitive root modulo 881; consequently, the decimal expansion of 1⁄881 has a repetend of length 880, making 881 a full reptend prime in base‑10.
Occurrences in other contexts
- Historical year – The Gregorian year 881 AD is noted in historical chronicles for various political and military events, but the number itself carries no intrinsic significance beyond its use as a calendar year.
- Telecommunications – The International Telecommunication Union (ITU) has allocated the three‑digit code “881” for the Global Mobile Satellite System (GMSS) numbering plan, designating certain satellite‑based mobile services.
- Transportation – In some national road networks, the designation “881” is used for specific highway or route numbers; the numbering is a matter of administrative assignment rather than an intrinsic property of the number.