28138990 has 32 divisors (see below), whose sum is σ = 57166560. Its totient is φ = 9878400.

The previous prime is 28138987. The next prime is 28139003. The reversal of 28138990 is 9983182.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1221 + ... + 7600.

It is an arithmetic number, because the mean of its divisors is an integer number (1786455).

Almost surely, 2^28138990 is an apocalyptic number.

28138990 is an abundant number, since it is smaller than the sum of its proper divisors (29027570).

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

28138990 is a wasteful number, since it uses less digits than its factorization.

28138990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8868.

The product of its (nonzero) digits is 31104, while the sum is 40.

The square root of 28138990 is about 5304.6196847653. The cubic root of 28138990 is about 304.1605151276.

The spelling of 28138990 in words is "twenty-eight million, one hundred thirty-eight thousand, nine hundred ninety".