28705638 has 16 divisors (see below), whose sum is σ = 61827696. Its totient is φ = 8832480.

The previous prime is 28705631. The next prime is 28705657. The reversal of 28705638 is 83650782.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a junction number, because it is equal to n+sod(n) for n = 28705596 and 28705605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28705631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 183933 + ... + 184088.

It is an arithmetic number, because the mean of its divisors is an integer number (3864231).

Almost surely, 2^28705638 is an apocalyptic number.

28705638 is an abundant number, since it is smaller than the sum of its proper divisors (33122058).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28705638 is a wasteful number, since it uses less digits than its factorization.

28705638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 368039.

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 28705638 is about 5357.7642725301. The cubic root of 28705638 is about 306.1886358795.

The spelling of 28705638 in words is "twenty-eight million, seven hundred five thousand, six hundred thirty-eight".