28091820 has 48 divisors (see below), whose sum is σ = 83287008. Its totient is φ = 7050240.

The previous prime is 28091813. The next prime is 28091831. The reversal of 28091820 is 2819082.

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

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 15 ways as a sum of consecutive naturals, for example, 12751 + ... + 14790.

It is an arithmetic number, because the mean of its divisors is an integer number (1735146).

Almost surely, 2^28091820 is an apocalyptic number.

28091820 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28091820 is an abundant number, since it is smaller than the sum of its proper divisors (55195188).

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

28091820 is a wasteful number, since it uses less digits than its factorization.

28091820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27570 (or 27568 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The square root of 28091820 is about 5300.1716953321. The cubic root of 28091820 is about 303.9904631126.

The spelling of 28091820 in words is "twenty-eight million, ninety-one thousand, eight hundred twenty".