28684220 has 48 divisors (see below), whose sum is σ = 63479808. Its totient is φ = 10866240.

The previous prime is 28684211. The next prime is 28684223. The reversal of 28684220 is 2248682.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28684223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 58175 + ... + 58665.

It is an arithmetic number, because the mean of its divisors is an integer number (1322496).

Almost surely, 2^28684220 is an apocalyptic number.

28684220 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 28684220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31739904).

28684220 is an abundant number, since it is smaller than the sum of its proper divisors (34795588).

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

28684220 is a wasteful number, since it uses less digits than its factorization.

28684220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 650 (or 648 counting only the distinct ones).

The product of its (nonzero) digits is 12288, while the sum is 32.

The square root of 28684220 is about 5355.7651180760. The cubic root of 28684220 is about 306.1124652460.

The spelling of 28684220 in words is "twenty-eight million, six hundred eighty-four thousand, two hundred twenty".