128216566 has 4 divisors (see below), whose sum is σ = 192324852. Its totient is φ = 64108282.

The previous prime is 128216531. The next prime is 128216603. The reversal of 128216566 is 665612821.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 32054140 + ... + 32054143.

It is an arithmetic number, because the mean of its divisors is an integer number (48081213).

Almost surely, 2^128216566 is an apocalyptic number.

128216566 is a deficient number, since it is larger than the sum of its proper divisors (64108286).

128216566 is an equidigital number, since it uses as much as digits as its factorization.

128216566 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64108285.

The product of its digits is 34560, while the sum is 37.

The square root of 128216566 is about 11323.2754095271. The cubic root of 128216566 is about 504.2524848776.

The spelling of 128216566 in words is "one hundred twenty-eight million, two hundred sixteen thousand, five hundred sixty-six".