128609993 has 4 divisors (see below), whose sum is σ = 135378960. Its totient is φ = 121841028.

The previous prime is 128609977. The next prime is 128610011. The reversal of 128609993 is 399906821.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 399906821 = 4597 ⋅86993.

It is a cyclic number.

It is not a de Polignac number, because 128609993 - 2⁴ = 128609977 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (128609903) 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, 3384455 + ... + 3384492.

It is an arithmetic number, because the mean of its divisors is an integer number (33844740).

Almost surely, 2^128609993 is an apocalyptic number.

It is an amenable number.

128609993 is a deficient number, since it is larger than the sum of its proper divisors (6768967).

128609993 is an equidigital number, since it uses as much as digits as its factorization.

128609993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6768966.

The product of its (nonzero) digits is 209952, while the sum is 47.

The square root of 128609993 is about 11340.6345942368. The cubic root of 128609993 is about 504.7677172438.

The spelling of 128609993 in words is "one hundred twenty-eight million, six hundred nine thousand, nine hundred ninety-three".