1991188 has 12 divisors (see below), whose sum is σ = 3498880. Its totient is φ = 991512.

The previous prime is 1991177. The next prime is 1991189. The reversal of 1991188 is 8811991.

It is a happy number.

It is a hoax number, since the sum of its digits (37) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991189) 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, 253 + ... + 2011.

2^1991188 is an apocalyptic number.

It is an amenable number.

1991188 is a deficient number, since it is larger than the sum of its proper divisors (1507692).

1991188 is a wasteful number, since it uses less digits than its factorization.

1991188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2046 (or 2044 counting only the distinct ones).

The product of its digits is 5184, while the sum is 37.

The square root of 1991188 is about 1411.0946105772. The cubic root of 1991188 is about 125.8067921548.

The spelling of 1991188 in words is "one million, nine hundred ninety-one thousand, one hundred eighty-eight".