665128 has 16 divisors (see below), whose sum is σ = 1265760. Its totient is φ = 327600.

The previous prime is 665123. The next prime is 665131. The reversal of 665128 is 821566.

It is a junction number, because it is equal to n+sod(n) for n = 665096 and 665105.

It is not an unprimeable number, because it can be changed into a prime (665123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18 + ... + 1153.

It is an arithmetic number, because the mean of its divisors is an integer number (79110).

2⁶⁶⁵¹²⁸ is an apocalyptic number.

It is an amenable number.

665128 is a deficient number, since it is larger than the sum of its proper divisors (600632).

665128 is a wasteful number, since it uses less digits than its factorization.

665128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1248 (or 1244 counting only the distinct ones).

The product of its digits is 2880, while the sum is 28.

The square root of 665128 is about 815.5537995743. The cubic root of 665128 is about 87.2907872452.

The spelling of 665128 in words is "six hundred sixty-five thousand, one hundred twenty-eight".