1981803 has 4 divisors (see below), whose sum is σ = 2642408. Its totient is φ = 1321200.

The previous prime is 1981787. The next prime is 1981813. The reversal of 1981803 is 3081891.

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

It is not a de Polignac number, because 1981803 - 2⁴ = 1981787 is a prime.

It is a D-number.

It is a Duffinian number.

1981803 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1981813) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 330298 + ... + 330303.

It is an arithmetic number, because the mean of its divisors is an integer number (660602).

2^1981803 is an apocalyptic number.

1981803 is a deficient number, since it is larger than the sum of its proper divisors (660605).

1981803 is an equidigital number, since it uses as much as digits as its factorization.

1981803 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 660604.

The product of its (nonzero) digits is 1728, while the sum is 30.

The square root of 1981803 is about 1407.7652503170. The cubic root of 1981803 is about 125.6088271549.

The spelling of 1981803 in words is "one million, nine hundred eighty-one thousand, eight hundred three".