28221555 has 16 divisors (see below), whose sum is σ = 47531520. Its totient is φ = 14259168.

The previous prime is 28221551. The next prime is 28221601. The reversal of 28221555 is 55512282.

It is not a de Polignac number, because 28221555 - 2² = 28221551 is a prime.

It is not an unprimeable number, because it can be changed into a prime (28221551) by changing a digit.

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, 49227 + ... + 49796.

It is an arithmetic number, because the mean of its divisors is an integer number (2970720).

Almost surely, 2^28221555 is an apocalyptic number.

28221555 is a deficient number, since it is larger than the sum of its proper divisors (19309965).

28221555 is a wasteful number, since it uses less digits than its factorization.

28221555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99050.

The product of its digits is 8000, while the sum is 30.

The square root of 28221555 is about 5312.3963519301. The cubic root of 28221555 is about 304.4577123714.

The spelling of 28221555 in words is "twenty-eight million, two hundred twenty-one thousand, five hundred fifty-five".