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8191 is a prime number

8191 has 2 divisors, whose sum is σ = 8192. Its totient is φ = 8190.

The previous prime is 8179. The next prime is 8209. The reversal of 8191 is 1918.

8191 is nontrivially palindromic in base 2.

It is a Cunningham number, because it is equal to 213-1.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 8191 - 211 = 6143 is a prime.

It is a Chen prime.

It is the 91-st Hogben number.

8191 is a lucky number.

8191 is a nontrivial repdigit in base 2.

It is a plaindrome in base 2, base 4, base 8 and base 16.

It is a nialpdrome in base 2.

It is a zygodrome in base 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8101) by changing a digit.

It is a nontrivial repunit in base 2 and in base 90.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4095 + 4096.

It is an arithmetic number, because the mean of its divisors is an integer number (4096).

28191 is an apocalyptic number.

8191 is a deficient number, since it is larger than the sum of its proper divisors (1).

8191 is an equidigital number, since it uses as much as digits as its factorization.

8191 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72, while the sum is 19.

The square root of 8191 is about 90.5041435516. The cubic root of 8191 is about 20.1579165038.

It can be divided in two parts, 819 and 1, that added together give a triangular number (820 = T40).

The spelling of 8191 in words is "eight thousand, one hundred ninety-one".