28281638 has 32 divisors (see below), whose sum is σ = 53699328. Its totient is φ = 10850400.

The previous prime is 28281629. The next prime is 28281679. The reversal of 28281638 is 83618282.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8948 + ... + 11688.

It is an arithmetic number, because the mean of its divisors is an integer number (1678104).

Almost surely, 2^28281638 is an apocalyptic number.

28281638 is a deficient number, since it is larger than the sum of its proper divisors (25417690).

28281638 is a wasteful number, since it uses less digits than its factorization.

28281638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2828.

The product of its digits is 36864, while the sum is 38.

The square root of 28281638 is about 5318.0483262189. The cubic root of 28281638 is about 304.6736202294.

The spelling of 28281638 in words is "twenty-eight million, two hundred eighty-one thousand, six hundred thirty-eight".