128909805 has 16 divisors (see below), whose sum is σ = 207494784. Its totient is φ = 68338880.

The previous prime is 128909797. The next prime is 128909819. The reversal of 128909805 is 508909821.

It is a happy number.

It is not a de Polignac number, because 128909805 - 2³ = 128909797 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23226 + ... + 28235.

It is an arithmetic number, because the mean of its divisors is an integer number (12968424).

Almost surely, 2^128909805 is an apocalyptic number.

128909805 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

128909805 is a deficient number, since it is larger than the sum of its proper divisors (78584979).

128909805 is a wasteful number, since it uses less digits than its factorization.

128909805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51636.

The product of its (nonzero) digits is 51840, while the sum is 42.

The square root of 128909805 is about 11353.8453838336. The cubic root of 128909805 is about 505.1596462873.

The spelling of 128909805 in words is "one hundred twenty-eight million, nine hundred nine thousand, eight hundred five".