128518321 has 4 divisors (see below), whose sum is σ = 128552292. Its totient is φ = 128484352.

The previous prime is 128518309. The next prime is 128518349. The reversal of 128518321 is 123815821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 123815821 = 89 ⋅1391189.

It can be written as a sum of positive squares in 2 ways, for example, as 65934400 + 62583921 = 8120^2 + 7911^2 .

It is a cyclic number.

It is not a de Polignac number, because 128518321 - 2¹¹ = 128516273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128518301) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10480 + ... + 19153.

It is an arithmetic number, because the mean of its divisors is an integer number (32138073).

Almost surely, 2^128518321 is an apocalyptic number.

It is an amenable number.

128518321 is a deficient number, since it is larger than the sum of its proper divisors (33971).

128518321 is an equidigital number, since it uses as much as digits as its factorization.

128518321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33970.

The product of its digits is 3840, while the sum is 31.

The square root of 128518321 is about 11336.5921246202. The cubic root of 128518321 is about 504.6477575014.

The spelling of 128518321 in words is "one hundred twenty-eight million, five hundred eighteen thousand, three hundred twenty-one".