28081220 has 12 divisors (see below), whose sum is σ = 58970604. Its totient is φ = 11232480.

The previous prime is 28081219. The next prime is 28081223. The reversal of 28081220 is 2218082.

It can be written as a sum of positive squares in 2 ways, for example, as 7214596 + 20866624 = 2686^2 + 4568^2 .

It is a hoax number, since the sum of its digits (23) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (28081223) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 702011 + ... + 702050.

It is an arithmetic number, because the mean of its divisors is an integer number (4914217).

Almost surely, 2^28081220 is an apocalyptic number.

28081220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28081220 is an abundant number, since it is smaller than the sum of its proper divisors (30889384).

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

28081220 is a wasteful number, since it uses less digits than its factorization.

28081220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1404070 (or 1404068 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 23.

The square root of 28081220 is about 5299.1716333782. The cubic root of 28081220 is about 303.9522229857.

The spelling of 28081220 in words is "twenty-eight million, eighty-one thousand, two hundred twenty".