128215666 has 8 divisors (see below), whose sum is σ = 203636700. Its totient is φ = 60336768.

The previous prime is 128215643. The next prime is 128215687. The reversal of 128215666 is 666512821.

It can be written as a sum of positive squares in 2 ways, for example, as 128165041 + 50625 = 11321^2 + 225^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1885491 + ... + 1885558.

Almost surely, 2^128215666 is an apocalyptic number.

128215666 is a deficient number, since it is larger than the sum of its proper divisors (75421034).

128215666 is a wasteful number, since it uses less digits than its factorization.

128215666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3771068.

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

The square root of 128215666 is about 11323.2356683061. The cubic root of 128215666 is about 504.2513050293.

It can be divided in two parts, 128215 and 666, that added together give a square (128881 = 359²).

The spelling of 128215666 in words is "one hundred twenty-eight million, two hundred fifteen thousand, six hundred sixty-six".