28005138 has 48 divisors (see below), whose sum is σ = 70836480. Its totient is φ = 7829568.

The previous prime is 28005079. The next prime is 28005139. The reversal of 28005138 is 83150082.

It is a happy number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28005139) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3558 + ... + 8286.

It is an arithmetic number, because the mean of its divisors is an integer number (1475760).

Almost surely, 2^28005138 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28005138, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35418240).

28005138 is an abundant number, since it is smaller than the sum of its proper divisors (42831342).

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

28005138 is a wasteful number, since it uses less digits than its factorization.

28005138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4791 (or 4788 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 28005138 is about 5291.9880952247. The cubic root of 28005138 is about 303.6774698541.

The spelling of 28005138 in words is "twenty-eight million, five thousand, one hundred thirty-eight".