389851991 has 2 divisors, whose sum is σ = 389851992. Its totient is φ = 389851990.

The previous prime is 389851967. The next prime is 389851993. The reversal of 389851991 is 199158983.

It is a strong prime.

It is an emirp because it is prime and its reverse (199158983) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 389851991 - 2⁶ = 389851927 is a prime.

It is a Sophie Germain prime.

Together with 389851993, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (389851993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 194925995 + 194925996.

It is an arithmetic number, because the mean of its divisors is an integer number (194925996).

Almost surely, 2^389851991 is an apocalyptic number.

389851991 is a deficient number, since it is larger than the sum of its proper divisors (1).

389851991 is an equidigital number, since it uses as much as digits as its factorization.

389851991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 699840, while the sum is 53.

The square root of 389851991 is about 19744.6699389987. The cubic root of 389851991 is about 730.5219204977.

The spelling of 389851991 in words is "three hundred eighty-nine million, eight hundred fifty-one thousand, nine hundred ninety-one".