1998689 has 16 divisors (see below), whose sum is σ = 2526336. Its totient is φ = 1536000.

The previous prime is 1998679. The next prime is 1998691. The reversal of 1998689 is 9868991.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1998689 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1998679) 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, 7649 + ... + 7905.

It is an arithmetic number, because the mean of its divisors is an integer number (157896).

2^1998689 is an apocalyptic number.

It is an amenable number.

1998689 is a deficient number, since it is larger than the sum of its proper divisors (527647).

1998689 is a wasteful number, since it uses less digits than its factorization.

1998689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 376.

The product of its digits is 279936, while the sum is 50.

The square root of 1998689 is about 1413.7499778957. The cubic root of 1998689 is about 125.9645696972.

It can be divided in two parts, 199 and 8689, that added together give a palindrome (8888).

The spelling of 1998689 in words is "one million, nine hundred ninety-eight thousand, six hundred eighty-nine".