28065357721 has 2 divisors, whose sum is σ = 28065357722. Its totient is φ = 28065357720.

The previous prime is 28065357659. The next prime is 28065357743. The reversal of 28065357721 is 12775356082.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18601959321 + 9463398400 = 136389^2 + 97280^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28065357721 is a prime.

It is not a weakly prime, because it can be changed into another prime (28065357791) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14032678860 + 14032678861.

It is an arithmetic number, because the mean of its divisors is an integer number (14032678861).

Almost surely, 2^28065357721 is an apocalyptic number.

It is an amenable number.

28065357721 is a deficient number, since it is larger than the sum of its proper divisors (1).

28065357721 is an equidigital number, since it uses as much as digits as its factorization.

28065357721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 705600, while the sum is 46.

The spelling of 28065357721 in words is "twenty-eight billion, sixty-five million, three hundred fifty-seven thousand, seven hundred twenty-one".