991003 has 4 divisors (see below), whose sum is σ = 1067248. Its totient is φ = 914760.

The previous prime is 990989. The next prime is 991009. The reversal of 991003 is 300199.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 300199 = 317 ⋅947.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991003 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991009) 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, 38103 + ... + 38128.

It is an arithmetic number, because the mean of its divisors is an integer number (266812).

2⁹⁹¹⁰⁰³ is an apocalyptic number.

991003 is a deficient number, since it is larger than the sum of its proper divisors (76245).

991003 is a wasteful number, since it uses less digits than its factorization.

991003 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76244.

The product of its (nonzero) digits is 243, while the sum is 22.

The square root of 991003 is about 995.4913359744. The cubic root of 991003 is about 99.6991960773.

The spelling of 991003 in words is "nine hundred ninety-one thousand, three".