391385989 has 2 divisors, whose sum is σ = 391385990. Its totient is φ = 391385988.

The previous prime is 391385977. The next prime is 391386013. The reversal of 391385989 is 989583193.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 355888225 + 35497764 = 18865^2 + 5958^2 .

It is a cyclic number.

It is not a de Polignac number, because 391385989 - 2⁷ = 391385861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (391385689) 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 as a sum of consecutive naturals, namely, 195692994 + 195692995.

It is an arithmetic number, because the mean of its divisors is an integer number (195692995).

Almost surely, 2^391385989 is an apocalyptic number.

It is an amenable number.

391385989 is a deficient number, since it is larger than the sum of its proper divisors (1).

391385989 is an equidigital number, since it uses as much as digits as its factorization.

391385989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2099520, while the sum is 55.

The square root of 391385989 is about 19783.4776770921. The cubic root of 391385989 is about 731.4788242999.

The spelling of 391385989 in words is "three hundred ninety-one million, three hundred eighty-five thousand, nine hundred eighty-nine".