1998609 has 4 divisors (see below), whose sum is σ = 2664816. Its totient is φ = 1332404.

The previous prime is 1998589. The next prime is 1998611. The reversal of 1998609 is 9068991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1998609 - 2¹⁹ = 1474321 is a prime.

It is a D-number.

It is not an unprimeable number, because it can be changed into a prime (1998679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 333099 + ... + 333104.

It is an arithmetic number, because the mean of its divisors is an integer number (666204).

2^1998609 is an apocalyptic number.

It is an amenable number.

1998609 is a deficient number, since it is larger than the sum of its proper divisors (666207).

1998609 is an equidigital number, since it uses as much as digits as its factorization.

1998609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 666206.

The product of its (nonzero) digits is 34992, while the sum is 42.

The square root of 1998609 is about 1413.7216840666. The cubic root of 1998609 is about 125.9628890455.

The spelling of 1998609 in words is "one million, nine hundred ninety-eight thousand, six hundred nine".