128509665 has 8 divisors (see below), whose sum is σ = 205615488. Its totient is φ = 68538480.

The previous prime is 128509657. The next prime is 128509691. The reversal of 128509665 is 566905821.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 128509665 - 2³ = 128509657 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4283641 + ... + 4283670.

It is an arithmetic number, because the mean of its divisors is an integer number (25701936).

Almost surely, 2^128509665 is an apocalyptic number.

128509665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

128509665 is a deficient number, since it is larger than the sum of its proper divisors (77105823).

128509665 is an equidigital number, since it uses as much as digits as its factorization.

128509665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8567319.

The product of its (nonzero) digits is 129600, while the sum is 42.

The square root of 128509665 is about 11336.2103456137. The cubic root of 128509665 is about 504.6364275239.

The spelling of 128509665 in words is "one hundred twenty-eight million, five hundred nine thousand, six hundred sixty-five".