1981985 has 16 divisors (see below), whose sum is σ = 2588160. Its totient is φ = 1451520.

The previous prime is 1981963. The next prime is 1981997. The reversal of 1981985 is 5891891.

It is not a de Polignac number, because 1981985 - 2⁶ = 1981921 is a prime.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 2609 + ... + 3281.

It is an arithmetic number, because the mean of its divisors is an integer number (161760).

2^1981985 is an apocalyptic number.

It is an amenable number.

1981985 is a deficient number, since it is larger than the sum of its proper divisors (606175).

1981985 is a wasteful number, since it uses less digits than its factorization.

1981985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 728.

The product of its digits is 25920, while the sum is 41.

The square root of 1981985 is about 1407.8298902921. The cubic root of 1981985 is about 125.6126721565.

The spelling of 1981985 in words is "one million, nine hundred eighty-one thousand, nine hundred eighty-five".