128537509 has 2 divisors, whose sum is σ = 128537510. Its totient is φ = 128537508.

The previous prime is 128537491. The next prime is 128537531. The reversal of 128537509 is 905735821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 78269409 + 50268100 = 8847^2 + 7090^2 .

It is a cyclic number.

It is not a de Polignac number, because 128537509 - 2⁹ = 128536997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (128537579) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64268754 + 64268755.

It is an arithmetic number, because the mean of its divisors is an integer number (64268755).

Almost surely, 2^128537509 is an apocalyptic number.

It is an amenable number.

128537509 is a deficient number, since it is larger than the sum of its proper divisors (1).

128537509 is an equidigital number, since it uses as much as digits as its factorization.

128537509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 75600, while the sum is 40.

The square root of 128537509 is about 11337.4383791049. The cubic root of 128537509 is about 504.6728711694.

The spelling of 128537509 in words is "one hundred twenty-eight million, five hundred thirty-seven thousand, five hundred nine".