1981859 has 8 divisors (see below), whose sum is σ = 2181360. Its totient is φ = 1800480.

The previous prime is 1981853. The next prime is 1981867. The reversal of 1981859 is 9581891.

It is a de Polignac number, because none of the positive numbers 2^k-1981859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1981853) 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 7 ways as a sum of consecutive naturals, for example, 587 + ... + 2075.

It is an arithmetic number, because the mean of its divisors is an integer number (272670).

2^1981859 is an apocalyptic number.

1981859 is a deficient number, since it is larger than the sum of its proper divisors (199501).

1981859 is an equidigital number, since it uses as much as digits as its factorization.

1981859 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1522 (or 1500 counting only the distinct ones).

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

The square root of 1981859 is about 1407.7851398562. The cubic root of 1981859 is about 125.6100102574.

The spelling of 1981859 in words is "one million, nine hundred eighty-one thousand, eight hundred fifty-nine".