28109638 has 4 divisors (see below), whose sum is σ = 42164460. Its totient is φ = 14054818.

The previous prime is 28109629. The next prime is 28109639. The reversal of 28109638 is 83690182.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83690182 = 2 ⋅41845091.

It is a junction number, because it is equal to n+sod(n) for n = 28109597 and 28109606.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28109639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 7027408 + ... + 7027411.

It is an arithmetic number, because the mean of its divisors is an integer number (10541115).

Almost surely, 2^28109638 is an apocalyptic number.

28109638 is a deficient number, since it is larger than the sum of its proper divisors (14054822).

28109638 is a wasteful number, since it uses less digits than its factorization.

28109638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14054821.

The product of its (nonzero) digits is 20736, while the sum is 37.

The square root of 28109638 is about 5301.8523178225. The cubic root of 28109638 is about 304.0547209320.

The spelling of 28109638 in words is "twenty-eight million, one hundred nine thousand, six hundred thirty-eight".