28138216 has 16 divisors (see below), whose sum is σ = 52951140. Its totient is φ = 14017920.

The previous prime is 28138199. The next prime is 28138217. The reversal of 28138216 is 61283182.

It can be written as a sum of positive squares in 2 ways, for example, as 24700900 + 3437316 = 4970^2 + 1854^2 .

It is not an unprimeable number, because it can be changed into a prime (28138217) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4011 + ... + 8506.

Almost surely, 2^28138216 is an apocalyptic number.

It is an amenable number.

28138216 is a deficient number, since it is larger than the sum of its proper divisors (24812924).

28138216 is a wasteful number, since it uses less digits than its factorization.

28138216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12804 (or 12800 counting only the distinct ones).

The product of its digits is 4608, while the sum is 31.

The square root of 28138216 is about 5304.5467289864. The cubic root of 28138216 is about 304.1577263234.

The spelling of 28138216 in words is "twenty-eight million, one hundred thirty-eight thousand, two hundred sixteen".