28138904 has 16 divisors (see below), whose sum is σ = 52984800. Its totient is φ = 14009632.

The previous prime is 28138897. The next prime is 28138937. The reversal of 28138904 is 40983182.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5447 + ... + 9270.

It is an arithmetic number, because the mean of its divisors is an integer number (3311550).

Almost surely, 2^28138904 is an apocalyptic number.

It is an amenable number.

28138904 is a deficient number, since it is larger than the sum of its proper divisors (24845896).

28138904 is a wasteful number, since it uses less digits than its factorization.

28138904 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14962 (or 14958 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 28138904 is about 5304.6115786172. The cubic root of 28138904 is about 304.1602052630.

The spelling of 28138904 in words is "twenty-eight million, one hundred thirty-eight thousand, nine hundred four".