1989391 has 4 divisors (see below), whose sum is σ = 2106432. Its totient is φ = 1872352.

The previous prime is 1989353. The next prime is 1989401. The reversal of 1989391 is 1939891.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1989391 - 2⁷ = 1989263 is a prime.

It is a super-3 number, since 3×1989391³ = 23620098333701110413, which contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1989341) 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, 58495 + ... + 58528.

It is an arithmetic number, because the mean of its divisors is an integer number (526608).

2^1989391 is an apocalyptic number.

1989391 is a deficient number, since it is larger than the sum of its proper divisors (117041).

1989391 is a wasteful number, since it uses less digits than its factorization.

1989391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 117040.

The product of its digits is 17496, while the sum is 40.

The square root of 1989391 is about 1410.4577271227. The cubic root of 1989391 is about 125.7689348808.

The spelling of 1989391 in words is "one million, nine hundred eighty-nine thousand, three hundred ninety-one".