128643993 has 12 divisors (see below), whose sum is σ = 186001920. Its totient is φ = 85678296.

The previous prime is 128643979. The next prime is 128644027. The reversal of 128643993 is 399346821.

It is a happy number.

128643993 is a `hidden beast` number, since 128 + 6 + 439 + 93 = 666.

It is not a de Polignac number, because 128643993 - 2¹⁷ = 128512921 is a prime.

It is not an unprimeable number, because it can be changed into a prime (128643923) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3448 + ... + 16406.

It is an arithmetic number, because the mean of its divisors is an integer number (15500160).

Almost surely, 2^128643993 is an apocalyptic number.

It is an amenable number.

128643993 is a deficient number, since it is larger than the sum of its proper divisors (57357927).

128643993 is a wasteful number, since it uses less digits than its factorization.

128643993 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14068 (or 14065 counting only the distinct ones).

The product of its digits is 279936, while the sum is 45.

The square root of 128643993 is about 11342.1335294556. The cubic root of 128643993 is about 504.8121943223.

The spelling of 128643993 in words is "one hundred twenty-eight million, six hundred forty-three thousand, nine hundred ninety-three".