128217321 has 24 divisors (see below), whose sum is σ = 192541440. Its totient is φ = 82148256.

The previous prime is 128217319. The next prime is 128217343. The reversal of 128217321 is 123712821.

128217321 is a `hidden beast` number, since 128 + 217 + 321 = 666.

It is not a de Polignac number, because 128217321 - 2¹ = 128217319 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (128217311) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 25320 + ... + 29958.

It is an arithmetic number, because the mean of its divisors is an integer number (8022560).

Almost surely, 2^128217321 is an apocalyptic number.

It is an amenable number.

128217321 is a deficient number, since it is larger than the sum of its proper divisors (64324119).

128217321 is a wasteful number, since it uses less digits than its factorization.

128217321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4765 (or 4762 counting only the distinct ones).

The product of its digits is 1344, while the sum is 27.

The square root of 128217321 is about 11323.3087478881. The cubic root of 128217321 is about 504.2534746350.

The spelling of 128217321 in words is "one hundred twenty-eight million, two hundred seventeen thousand, three hundred twenty-one".