1191391 has 4 divisors (see below), whose sum is σ = 1210984. Its totient is φ = 1171800.

The previous prime is 1191373. The next prime is 1191409. The reversal of 1191391 is 1931911.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1931911 = 541 ⋅3571.

It is an interprime number because it is at equal distance from previous prime (1191373) and next prime (1191409).

It is a cyclic number.

It is not a de Polignac number, because 1191391 - 2¹³ = 1183199 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1191301) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 9705 + ... + 9826.

It is an arithmetic number, because the mean of its divisors is an integer number (302746).

2^1191391 is an apocalyptic number.

1191391 is a deficient number, since it is larger than the sum of its proper divisors (19593).

1191391 is an equidigital number, since it uses as much as digits as its factorization.

1191391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19592.

The product of its digits is 243, while the sum is 25.

The square root of 1191391 is about 1091.5085890638. The cubic root of 1191391 is about 106.0111237881.

The spelling of 1191391 in words is "one million, one hundred ninety-one thousand, three hundred ninety-one".