991303909 has 2 divisors, whose sum is σ = 991303910. Its totient is φ = 991303908.

The previous prime is 991303903. The next prime is 991303987. The reversal of 991303909 is 909303199.

991303909 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 760932225 + 230371684 = 27585^2 + 15178^2 .

It is a cyclic number.

It is not a de Polignac number, because 991303909 - 2¹³ = 991295717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991303903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495651954 + 495651955.

It is an arithmetic number, because the mean of its divisors is an integer number (495651955).

Almost surely, 2^991303909 is an apocalyptic number.

It is an amenable number.

991303909 is a deficient number, since it is larger than the sum of its proper divisors (1).

991303909 is an equidigital number, since it uses as much as digits as its factorization.

991303909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 59049, while the sum is 43.

The square root of 991303909 is about 31484.9791011523. The cubic root of 991303909 is about 997.0928597253.

The spelling of 991303909 in words is "nine hundred ninety-one million, three hundred three thousand, nine hundred nine".