128666 has 4 divisors (see below), whose sum is σ = 193002. Its totient is φ = 64332.

The previous prime is 128663. The next prime is 128669. The reversal of 128666 is 666821.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (128663) and next prime (128669).

It can be written as a sum of positive squares in only one way, i.e., 73441 + 55225 = 271^2 + 235^2 .

128666 is a modest number, since divided by 666 gives 128 as remainder.

It is not an unprimeable number, because it can be changed into a prime (128663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32165 + ... + 32168.

2¹²⁸⁶⁶⁶ is an apocalyptic number.

128666 is a deficient number, since it is larger than the sum of its proper divisors (64336).

128666 is an equidigital number, since it uses as much as digits as its factorization.

128666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64335.

The product of its digits is 3456, while the sum is 29.

The square root of 128666 is about 358.7004321157. The cubic root of 128666 is about 50.4840978588.

The spelling of 128666 in words is "one hundred twenty-eight thousand, six hundred sixty-six".