128217665813 has 4 divisors (see below), whose sum is σ = 129974072268. Its totient is φ = 126461259360.

The previous prime is 128217665801. The next prime is 128217665833. The reversal of 128217665813 is 318566712821.

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

It can be written as a sum of positive squares in 2 ways, for example, as 95739498724 + 32478167089 = 309418^2 + 180217^2 .

It is a cyclic number.

It is not a de Polignac number, because 128217665813 - 2¹⁰ = 128217664789 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128217665833) 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, 878203118 + ... + 878203263.

It is an arithmetic number, because the mean of its divisors is an integer number (32493518067).

Almost surely, 2^128217665813 is an apocalyptic number.

It is an amenable number.

128217665813 is a deficient number, since it is larger than the sum of its proper divisors (1756406455).

128217665813 is an equidigital number, since it uses as much as digits as its factorization.

128217665813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1756406454.

The product of its digits is 967680, while the sum is 50.

The spelling of 128217665813 in words is "one hundred twenty-eight billion, two hundred seventeen million, six hundred sixty-five thousand, eight hundred thirteen".