1998891 has 16 divisors (see below), whose sum is σ = 2994720. Its totient is φ = 1317600.

The previous prime is 1998881. The next prime is 1998917. The reversal of 1998891 is 1988991.

It is not a de Polignac number, because 1998891 - 2⁶ = 1998827 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1998881) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2361 + ... + 3093.

It is an arithmetic number, because the mean of its divisors is an integer number (187170).

2^1998891 is an apocalyptic number.

1998891 is a deficient number, since it is larger than the sum of its proper divisors (995829).

1998891 is a wasteful number, since it uses less digits than its factorization.

1998891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 843 (or 837 counting only the distinct ones).

The product of its digits is 46656, while the sum is 45.

The square root of 1998891 is about 1413.8214172943. The cubic root of 1998891 is about 125.9688131431.

The spelling of 1998891 in words is "one million, nine hundred ninety-eight thousand, eight hundred ninety-one".