1191 has 4 divisors (see below), whose sum is σ = 1592. Its totient is φ = 792.
The previous prime is 1187. The next prime is 1193. The reversal of 1191 is 1911.
It is a semiprime because it is the product of two primes.
It is not a de Polignac number, because 1191 - 22 = 1187 is a prime.
It is an Ulam number.
It is a D-number.
It is the 35-th Hogben number.
It is a Duffinian number.
It is a plaindrome in base 8.
It is a nialpdrome in base 7, base 11, base 12 and base 14.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (1193) by changing a digit.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 196 + ... + 201.
It is equal to the Eulerian number A(7, 2).
It is an arithmetic number, because the mean of its divisors is an integer number (398).
21191 is an apocalyptic number.
1191 is a deficient number, since it is larger than the sum of its proper divisors (401).
1191 is an equidigital number, since it uses as much as digits as its factorization.
1191 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 400.
The product of its digits is 9, while the sum is 12.
The square root of 1191 is about 34.5108678535. The cubic root of 1191 is about 10.5999525333.
It can be divided in two parts, 119 and 1, that added together give a triangular number (120 = T15).
The spelling of 1191 in words is "one thousand, one hundred ninety-one".
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