28281540 has 144 divisors (see below), whose sum is σ = 96550272. Its totient is φ = 6057984.

The previous prime is 28281511. The next prime is 28281553. The reversal of 28281540 is 4518282.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 28281498 and 28281507.

It is a congruent number.

It is an unprimeable number.

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, 121264 + ... + 121496.

It is an arithmetic number, because the mean of its divisors is an integer number (670488).

Almost surely, 2^28281540 is an apocalyptic number.

28281540 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 28281540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48275136).

28281540 is an abundant number, since it is smaller than the sum of its proper divisors (68268732).

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

28281540 is a wasteful number, since it uses less digits than its factorization.

28281540 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 286 (or 267 counting only the distinct ones).

The product of its (nonzero) digits is 5120, while the sum is 30.

The square root of 28281540 is about 5318.0391123045. The cubic root of 28281540 is about 304.6732683162.

The spelling of 28281540 in words is "twenty-eight million, two hundred eighty-one thousand, five hundred forty".