128681365 has 4 divisors (see below), whose sum is σ = 154417644. Its totient is φ = 102945088.

The previous prime is 128681363. The next prime is 128681401. The reversal of 128681365 is 563186821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 563186821 = 2551 ⋅220771.

It can be written as a sum of positive squares in 2 ways, for example, as 48525156 + 80156209 = 6966^2 + 8953^2 .

It is a cyclic number.

It is not a de Polignac number, because 128681365 - 2¹ = 128681363 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128681363) 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, 12868132 + ... + 12868141.

It is an arithmetic number, because the mean of its divisors is an integer number (38604411).

Almost surely, 2^128681365 is an apocalyptic number.

It is an amenable number.

128681365 is a deficient number, since it is larger than the sum of its proper divisors (25736279).

128681365 is an equidigital number, since it uses as much as digits as its factorization.

128681365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25736278.

The product of its digits is 69120, while the sum is 40.

The square root of 128681365 is about 11343.7808952747. The cubic root of 128681365 is about 504.8610734402.

The spelling of 128681365 in words is "one hundred twenty-eight million, six hundred eighty-one thousand, three hundred sixty-five".