1181391 has 4 divisors (see below), whose sum is σ = 1575192. Its totient is φ = 787592.

The previous prime is 1181329. The next prime is 1181407. The reversal of 1181391 is 1931811.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1181391 - 2⁷ = 1181263 is a prime.

It is an Ulam number.

It is a D-number.

1181391 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1181311) 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, 196896 + ... + 196901.

It is an arithmetic number, because the mean of its divisors is an integer number (393798).

2^1181391 is an apocalyptic number.

1181391 is a deficient number, since it is larger than the sum of its proper divisors (393801).

1181391 is an equidigital number, since it uses as much as digits as its factorization.

1181391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393800.

The product of its digits is 216, while the sum is 24.

The square root of 1181391 is about 1086.9181201912. The cubic root of 1181391 is about 105.7136868205.

The spelling of 1181391 in words is "one million, one hundred eighty-one thousand, three hundred ninety-one".