28138320 has 160 divisors (see below), whose sum is σ = 110826240. Its totient is φ = 6428160.

The previous prime is 28138307. The next prime is 28138321. The reversal of 28138320 is 2383182.

28138320 is a `hidden beast` number, since 281 + 383 + 2 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28138321) 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 31 ways as a sum of consecutive naturals, for example, 14190 + ... + 16050.

It is an arithmetic number, because the mean of its divisors is an integer number (692664).

Almost surely, 2^28138320 is an apocalyptic number.

28138320 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 28138320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (55413120).

28138320 is an abundant number, since it is smaller than the sum of its proper divisors (82687920).

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

28138320 is a wasteful number, since it uses less digits than its factorization.

28138320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1890 (or 1878 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The square root of 28138320 is about 5304.5565318884. The cubic root of 28138320 is about 304.1581010494.

The spelling of 28138320 in words is "twenty-eight million, one hundred thirty-eight thousand, three hundred twenty".