28725138 has 128 divisors (see below), whose sum is σ = 76204800. Its totient is φ = 7934976.

The previous prime is 28725101. The next prime is 28725139. The reversal of 28725138 is 83152782.

It is not an unprimeable number, because it can be changed into a prime (28725139) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 346045 + ... + 346127.

It is an arithmetic number, because the mean of its divisors is an integer number (595350).

Almost surely, 2^28725138 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28725138, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (38102400).

28725138 is an abundant number, since it is smaller than the sum of its proper divisors (47479662).

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

28725138 is a wasteful number, since it uses less digits than its factorization.

28725138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153 (or 147 counting only the distinct ones).

The product of its digits is 26880, while the sum is 36.

The square root of 28725138 is about 5359.5837524942. The cubic root of 28725138 is about 306.2579524243.

It can be divided in two parts, 287 and 25138, that added together give a triangular number (25425 = T₂₂₅).

The spelling of 28725138 in words is "twenty-eight million, seven hundred twenty-five thousand, one hundred thirty-eight".