128490639 has 4 divisors (see below), whose sum is σ = 171320856. Its totient is φ = 85660424.

The previous prime is 128490623. The next prime is 128490643. The reversal of 128490639 is 936094821.

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

It is a cyclic number.

It is not a de Polignac number, because 128490639 - 2⁴ = 128490623 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 128490639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (128490139) 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, 21415104 + ... + 21415109.

It is an arithmetic number, because the mean of its divisors is an integer number (42830214).

Almost surely, 2^128490639 is an apocalyptic number.

128490639 is a deficient number, since it is larger than the sum of its proper divisors (42830217).

128490639 is an equidigital number, since it uses as much as digits as its factorization.

128490639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42830216.

The product of its (nonzero) digits is 93312, while the sum is 42.

The square root of 128490639 is about 11335.3711452250. The cubic root of 128490639 is about 504.6115222985.

The spelling of 128490639 in words is "one hundred twenty-eight million, four hundred ninety thousand, six hundred thirty-nine".