1998009 has 12 divisors (see below), whose sum is σ = 3108196. Its totient is φ = 1229472.

The previous prime is 1997999. The next prime is 1998019. The reversal of 1998009 is 9008991.

It is an interprime number because it is at equal distance from previous prime (1997999) and next prime (1998019).

It can be written as a sum of positive squares in 2 ways, for example, as 558009 + 1440000 = 747^2 + 1200^2 .

It is not a de Polignac number, because 1998009 - 2⁸ = 1997753 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1998019) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8422 + ... + 8655.

2^1998009 is an apocalyptic number.

It is an amenable number.

1998009 is a deficient number, since it is larger than the sum of its proper divisors (1110187).

1998009 is a wasteful number, since it uses less digits than its factorization.

1998009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17096 (or 17093 counting only the distinct ones).

The product of its (nonzero) digits is 5832, while the sum is 36.

The square root of 1998009 is about 1413.5094622959. The cubic root of 1998009 is about 125.9502827282.

It can be divided in two parts, 199800 and 9, that added together give a square (199809 = 447²).

The spelling of 1998009 in words is "one million, nine hundred ninety-eight thousand, nine".