128934991 has 2 divisors, whose sum is σ = 128934992. Its totient is φ = 128934990.

The previous prime is 128934989. The next prime is 128935043. The reversal of 128934991 is 199439821.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 128934991 - 2¹ = 128934989 is a prime.

Together with 128934989, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128931991) 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, 64467495 + 64467496.

It is an arithmetic number, because the mean of its divisors is an integer number (64467496).

Almost surely, 2^128934991 is an apocalyptic number.

128934991 is a deficient number, since it is larger than the sum of its proper divisors (1).

128934991 is an equidigital number, since it uses as much as digits as its factorization.

128934991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 139968, while the sum is 46.

The square root of 128934991 is about 11354.9544693055. The cubic root of 128934991 is about 505.1925429893.

The spelling of 128934991 in words is "one hundred twenty-eight million, nine hundred thirty-four thousand, nine hundred ninety-one".