991303 has 4 divisors (see below), whose sum is σ = 994840. Its totient is φ = 987768.

The previous prime is 991273. The next prime is 991313. The reversal of 991303 is 303199.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991303 is a prime.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991313) 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, 1308 + ... + 1921.

It is an arithmetic number, because the mean of its divisors is an integer number (248710).

2⁹⁹¹³⁰³ is an apocalyptic number.

991303 is a deficient number, since it is larger than the sum of its proper divisors (3537).

991303 is a wasteful number, since it uses less digits than its factorization.

991303 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3536.

The product of its (nonzero) digits is 729, while the sum is 25.

The square root of 991303 is about 995.6420039351. The cubic root of 991303 is about 99.7092554956.

The spelling of 991303 in words is "nine hundred ninety-one thousand, three hundred three".