1998861 has 16 divisors (see below), whose sum is σ = 2833920. Its totient is φ = 1250480.

The previous prime is 1998839. The next prime is 1998881. The reversal of 1998861 is 1688991.

It is a cyclic number.

It is not a de Polignac number, because 1998861 - 2⁹ = 1998349 is a prime.

Its product of digits (31104) is a multiple of the sum of its prime divisors (576).

It is a Curzon number.

It is a congruent number.

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, 3826 + ... + 4316.

It is an arithmetic number, because the mean of its divisors is an integer number (177120).

2^1998861 is an apocalyptic number.

It is an amenable number.

1998861 is a deficient number, since it is larger than the sum of its proper divisors (835059).

1998861 is a wasteful number, since it uses less digits than its factorization.

1998861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 576.

The product of its digits is 31104, while the sum is 42.

The square root of 1998861 is about 1413.8108077108. The cubic root of 1998861 is about 125.9681829464.

The spelling of 1998861 in words is "one million, nine hundred ninety-eight thousand, eight hundred sixty-one".