128639 has 16 divisors (see below), whose sum is σ = 165888. Its totient is φ = 97152.

The previous prime is 128629. The next prime is 128657. The reversal of 128639 is 936821.

It is not a de Polignac number, because 128639 - 2¹² = 124543 is a prime.

It is an Ulam 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 (128629) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2714 + ... + 2760.

It is an arithmetic number, because the mean of its divisors is an integer number (10368).

2¹²⁸⁶³⁹ is an apocalyptic number.

128639 is a deficient number, since it is larger than the sum of its proper divisors (37249).

128639 is a wasteful number, since it uses less digits than its factorization.

128639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94.

The product of its digits is 2592, while the sum is 29.

The square root of 128639 is about 358.6627942790. The cubic root of 128639 is about 50.4805663223.

It can be divided in two parts, 128 and 639, that added together give a palindrome (767).

The spelling of 128639 in words is "one hundred twenty-eight thousand, six hundred thirty-nine".