1991003 has 4 divisors (see below), whose sum is σ = 2275440. Its totient is φ = 1706568.

The previous prime is 1990987. The next prime is 1991027. The reversal of 1991003 is 3001991.

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 1991003 - 2⁴ = 1990987 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1991003.

It is not an unprimeable number, because it can be changed into a prime (1991063) 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, 142208 + ... + 142221.

It is an arithmetic number, because the mean of its divisors is an integer number (568860).

2^1991003 is an apocalyptic number.

1991003 is a deficient number, since it is larger than the sum of its proper divisors (284437).

1991003 is an equidigital number, since it uses as much as digits as its factorization.

1991003 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284436.

The product of its (nonzero) digits is 243, while the sum is 23.

The square root of 1991003 is about 1411.0290571069. The cubic root of 1991003 is about 125.8028958246.

Adding to 1991003 its reverse (3001991), we get a palindrome (4992994).

The spelling of 1991003 in words is "one million, nine hundred ninety-one thousand, three".