28005500 has 48 divisors (see below), whose sum is σ = 62025600. Its totient is φ = 11044800.

The previous prime is 28005491. The next prime is 28005521. The reversal of 28005500 is 550082.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 39146 + ... + 39854.

It is an arithmetic number, because the mean of its divisors is an integer number (1292200).

Almost surely, 2^28005500 is an apocalyptic number.

28005500 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 28005500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31012800).

28005500 is an abundant number, since it is smaller than the sum of its proper divisors (34020100).

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

28005500 is a wasteful number, since it uses less digits than its factorization.

28005500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 807 (or 795 counting only the distinct ones).

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 28005500 is about 5292.0222977610. The cubic root of 28005500 is about 303.6787783137.

Adding to 28005500 its reverse (550082), we get a palindrome (28555582).

The spelling of 28005500 in words is "twenty-eight million, five thousand, five hundred".