128525809 has 2 divisors, whose sum is σ = 128525810. Its totient is φ = 128525808.

The previous prime is 128525807. The next prime is 128525821. The reversal of 128525809 is 908525821.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 123143409 + 5382400 = 11097^2 + 2320^2 .

It is a cyclic number.

It is not a de Polignac number, because 128525809 - 2¹ = 128525807 is a prime.

Together with 128525807, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (128525807) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 64262904 + 64262905.

It is an arithmetic number, because the mean of its divisors is an integer number (64262905).

Almost surely, 2^128525809 is an apocalyptic number.

It is an amenable number.

128525809 is a deficient number, since it is larger than the sum of its proper divisors (1).

128525809 is an equidigital number, since it uses as much as digits as its factorization.

128525809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 57600, while the sum is 40.

The square root of 128525809 is about 11336.9223777884. The cubic root of 128525809 is about 504.6575582546.

The spelling of 128525809 in words is "one hundred twenty-eight million, five hundred twenty-five thousand, eight hundred nine".