128693689 has 4 divisors (see below), whose sum is σ = 136263924. Its totient is φ = 121123456.

The previous prime is 128693687. The next prime is 128693701. The reversal of 128693689 is 986396821.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 986396821 = 1307 ⋅754703.

It can be written as a sum of positive squares in 2 ways, for example, as 52707600 + 75986089 = 7260^2 + 8717^2 .

It is a cyclic number.

It is not a de Polignac number, because 128693689 - 2¹ = 128693687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128693681) 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, 3785092 + ... + 3785125.

It is an arithmetic number, because the mean of its divisors is an integer number (34065981).

Almost surely, 2^128693689 is an apocalyptic number.

It is an amenable number.

128693689 is a deficient number, since it is larger than the sum of its proper divisors (7570235).

128693689 is an equidigital number, since it uses as much as digits as its factorization.

128693689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7570234.

The product of its digits is 1119744, while the sum is 52.

The square root of 128693689 is about 11344.3240874016. The cubic root of 128693689 is about 504.8771900169.

The spelling of 128693689 in words is "one hundred twenty-eight million, six hundred ninety-three thousand, six hundred eighty-nine".