1185991 has 4 divisors (see below), whose sum is σ = 1191400. Its totient is φ = 1180584.

The previous prime is 1185979. The next prime is 1185997. The reversal of 1185991 is 1995811.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1995811 = 31 ⋅64381.

It is a cyclic number.

It is not a de Polignac number, because 1185991 - 2¹¹ = 1183943 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1185997) 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, 2361 + ... + 2818.

It is an arithmetic number, because the mean of its divisors is an integer number (297850).

2^1185991 is an apocalyptic number.

1185991 is a deficient number, since it is larger than the sum of its proper divisors (5409).

1185991 is an equidigital number, since it uses as much as digits as its factorization.

1185991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5408.

The product of its digits is 3240, while the sum is 34.

The square root of 1185991 is about 1089.0321391033. The cubic root of 1185991 is about 105.8507154509.

The spelling of 1185991 in words is "one million, one hundred eighty-five thousand, nine hundred ninety-one".