28128100 has 144 divisors (see below), whose sum is σ = 82244736. Its totient is φ = 8064000.

The previous prime is 28128083. The next prime is 28128101. The reversal of 28128100 is 182182.

It is a super-2 number, since 2×28128100² = 1582380019220000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is not an unprimeable number, because it can be changed into a prime (28128101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 99960 + ... + 100240.

It is an arithmetic number, because the mean of its divisors is an integer number (571144).

Almost surely, 2^28128100 is an apocalyptic number.

28128100 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 28128100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41122368).

28128100 is an abundant number, since it is smaller than the sum of its proper divisors (54116636).

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

28128100 is a wasteful number, since it uses less digits than its factorization.

28128100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 326 (or 319 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 28128100 is about 5303.5931216488. The cubic root of 28128100 is about 304.1212725985.

It can be divided in two parts, 281 and 28100, that multiplied together give a square (7896100 = 2810²).

The spelling of 28128100 in words is "twenty-eight million, one hundred twenty-eight thousand, one hundred".