28291228 has 72 divisors (see below), whose sum is σ = 62052480. Its totient is φ = 11219040.

The previous prime is 28291217. The next prime is 28291229. The reversal of 28291228 is 82219282.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 28291193 and 28291202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28291229) 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, 264351 + ... + 264457.

It is an arithmetic number, because the mean of its divisors is an integer number (861840).

Almost surely, 2^28291228 is an apocalyptic number.

28291228 is a gapful number since it is divisible by the number (28) 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 28291228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31026240).

28291228 is an abundant number, since it is smaller than the sum of its proper divisors (33761252).

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

28291228 is a wasteful number, since it uses less digits than its factorization.

28291228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 215 (or 206 counting only the distinct ones).

The product of its digits is 9216, while the sum is 34.

The square root of 28291228 is about 5318.9498963611. The cubic root of 28291228 is about 304.7080535230.

The spelling of 28291228 in words is "twenty-eight million, two hundred ninety-one thousand, two hundred twenty-eight".