999903391 has 2 divisors, whose sum is σ = 999903392. Its totient is φ = 999903390.

The previous prime is 999903379. The next prime is 999903473. The reversal of 999903391 is 193309999.

It is a weak prime.

It is an emirp because it is prime and its reverse (193309999) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 999903391 - 2⁹ = 999902879 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999903301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499951695 + 499951696.

It is an arithmetic number, because the mean of its divisors is an integer number (499951696).

Almost surely, 2^999903391 is an apocalyptic number.

999903391 is a deficient number, since it is larger than the sum of its proper divisors (1).

999903391 is an equidigital number, since it uses as much as digits as its factorization.

999903391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 531441, while the sum is 52.

The square root of 999903391 is about 31621.2490423766. The cubic root of 999903391 is about 999.9677959629.

The spelling of 999903391 in words is "nine hundred ninety-nine million, nine hundred three thousand, three hundred ninety-one".