838999991 has 2 divisors, whose sum is σ = 838999992. Its totient is φ = 838999990.

The previous prime is 838999949. The next prime is 839000009. The reversal of 838999991 is 199999838.

838999991 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-838999991 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (838999391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 419499995 + 419499996.

It is an arithmetic number, because the mean of its divisors is an integer number (419499996).

Almost surely, 2^838999991 is an apocalyptic number.

838999991 is a deficient number, since it is larger than the sum of its proper divisors (1).

838999991 is an equidigital number, since it uses as much as digits as its factorization.

838999991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11337408, while the sum is 65.

The square root of 838999991 is about 28965.4965605632. The cubic root of 838999991 is about 943.1642238559.

The spelling of 838999991 in words is "eight hundred thirty-eight million, nine hundred ninety-nine thousand, nine hundred ninety-one".