1989409 has 4 divisors (see below), whose sum is σ = 1992340. Its totient is φ = 1986480.

The previous prime is 1989401. The next prime is 1989413. The reversal of 1989409 is 9049891.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 291600 + 1697809 = 540^2 + 1303^2 .

It is a cyclic number.

It is not a de Polignac number, because 1989409 - 2³ = 1989401 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1989401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139 + ... + 1999.

It is an arithmetic number, because the mean of its divisors is an integer number (498085).

2^1989409 is an apocalyptic number.

It is an amenable number.

1989409 is a deficient number, since it is larger than the sum of its proper divisors (2931).

1989409 is a wasteful number, since it uses less digits than its factorization.

1989409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2930.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 1989409 is about 1410.4641080155. The cubic root of 1989409 is about 125.7693141986.

The spelling of 1989409 in words is "one million, nine hundred eighty-nine thousand, four hundred nine".