28021568 has 14 divisors (see below), whose sum is σ = 55605426. Its totient is φ = 14010752.

The previous prime is 28021531. The next prime is 28021579. The reversal of 28021568 is 86512082.

It can be written as a sum of positive squares in only one way, i.e., 23892544 + 4129024 = 4888^2 + 2032^2 .

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 218855 + ... + 218982.

Almost surely, 2^28021568 is an apocalyptic number.

It is an amenable number.

28021568 is a deficient number, since it is larger than the sum of its proper divisors (27583858).

28021568 is an equidigital number, since it uses as much as digits as its factorization.

28021568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 437849 (or 437839 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 32.

The square root of 28021568 is about 5293.5402142612. The cubic root of 28021568 is about 303.7368452137.

The spelling of 28021568 in words is "twenty-eight million, twenty-one thousand, five hundred sixty-eight".