128512991 has 2 divisors, whose sum is σ = 128512992. Its totient is φ = 128512990.

The previous prime is 128512981. The next prime is 128512999. The reversal of 128512991 is 199215821.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-128512991 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128512999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64256495 + 64256496.

It is an arithmetic number, because the mean of its divisors is an integer number (64256496).

Almost surely, 2^128512991 is an apocalyptic number.

128512991 is a deficient number, since it is larger than the sum of its proper divisors (1).

128512991 is an equidigital number, since it uses as much as digits as its factorization.

128512991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 38.

The square root of 128512991 is about 11336.3570427188. The cubic root of 128512991 is about 504.6407810390.

The spelling of 128512991 in words is "one hundred twenty-eight million, five hundred twelve thousand, nine hundred ninety-one".