The Number
1991
One Thousand Nine Hundred and Ninety-One
Nearby Numbers
Positive, nonzero integers within three units
Scientific Notation
Scientific notation expresses a quantity as the product of its significand with 10 raised to an integer exponent.
1.991e3
Reciprocal
A number multiplied with its reciprocal is one.
0.0005022601707684581
The reciprocal of 1991.
Palindrome?
A numerical palindrome has the same value when all of its digits are reversed.
The number 1991 is a palindrome.
Not A Prime Number
A prime number is a positive integer that is divisible only by itself and one.
One thousand nine hundred and ninety-one is a composite number with 4 total factors (including 1 and itself). See primes in Base 10 Decimal
A Composite
Composites have more than just these two factors.
One thousand nine hundred and ninety-one is a composite number with 4 total factors (including 1 and itself).
Prime Factors
The number one thousand nine hundred and ninety-one has the following 2 prime factors:
Prime Factorization
The prime factorization of a positive integer is the unique list of prime factors together with their multiplicities
111
·
1811
= 1991
Base Conversions
The number one thousand nine hundred and ninety-one in 35 different bases