1991198 has 16 divisors (see below), whose sum is σ = 3371760. Its totient is φ = 873600.

The previous prime is 1991189. The next prime is 1991239. The reversal of 1991198 is 8911991.

It is a happy number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 923 + ... + 2198.

It is an arithmetic number, because the mean of its divisors is an integer number (210735).

2^1991198 is an apocalyptic number.

1991198 is a deficient number, since it is larger than the sum of its proper divisors (1380562).

1991198 is a wasteful number, since it uses less digits than its factorization.

1991198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3163.

The product of its digits is 5832, while the sum is 38.

The square root of 1991198 is about 1411.0981539213. The cubic root of 1991198 is about 125.8070027603.

It can be divided in two parts, 1 and 991198, that added together give a palindrome (991199).

The spelling of 1991198 in words is "one million, nine hundred ninety-one thousand, one hundred ninety-eight".