1197991 has 4 divisors (see below), whose sum is σ = 1207552. Its totient is φ = 1188432.

The previous prime is 1197971. The next prime is 1197997. The reversal of 1197991 is 1997911.

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 1197991 - 2⁹ = 1197479 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1197991.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1197997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4590 + ... + 4843.

It is an arithmetic number, because the mean of its divisors is an integer number (301888).

2^1197991 is an apocalyptic number.

1197991 is a deficient number, since it is larger than the sum of its proper divisors (9561).

1197991 is an equidigital number, since it uses as much as digits as its factorization.

1197991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9560.

The product of its digits is 5103, while the sum is 37.

The square root of 1197991 is about 1094.5277520465. The cubic root of 1197991 is about 106.2065215417.

The spelling of 1197991 in words is "one million, one hundred ninety-seven thousand, nine hundred ninety-one".