1989405 has 24 divisors (see below), whose sum is σ = 3762720. Its totient is φ = 964320.

The previous prime is 1989401. The next prime is 1989413. The reversal of 1989405 is 5049891.

It is not a de Polignac number, because 1989405 - 2² = 1989401 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1989405.

It is a congruent 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 (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1515 + ... + 2504.

It is an arithmetic number, because the mean of its divisors is an integer number (156780).

2^1989405 is an apocalyptic number.

1989405 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1989405 is a deficient number, since it is larger than the sum of its proper divisors (1773315).

1989405 is a wasteful number, since it uses less digits than its factorization.

1989405 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4041 (or 4038 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 36.

The square root of 1989405 is about 1410.4626900418. The cubic root of 1989405 is about 125.7692299060.

The spelling of 1989405 in words is "one million, nine hundred eighty-nine thousand, four hundred five".