28387321 has 2 divisors, whose sum is σ = 28387322. Its totient is φ = 28387320.

The previous prime is 28387309. The next prime is 28387339. The reversal of 28387321 is 12378382.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20575296 + 7812025 = 4536^2 + 2795^2 .

It is a cyclic number.

It is not a de Polignac number, because 28387321 - 2⁷ = 28387193 is a prime.

It is not a weakly prime, because it can be changed into another prime (28387391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14193660 + 14193661.

It is an arithmetic number, because the mean of its divisors is an integer number (14193661).

Almost surely, 2^28387321 is an apocalyptic number.

It is an amenable number.

28387321 is a deficient number, since it is larger than the sum of its proper divisors (1).

28387321 is an equidigital number, since it uses as much as digits as its factorization.

28387321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16128, while the sum is 34.

The square root of 28387321 is about 5327.9753190119. The cubic root of 28387321 is about 305.0526505900.

The spelling of 28387321 in words is "twenty-eight million, three hundred eighty-seven thousand, three hundred twenty-one".