28123545217 has 2 divisors, whose sum is σ = 28123545218. Its totient is φ = 28123545216.

The previous prime is 28123545199. The next prime is 28123545221. The reversal of 28123545217 is 71254532182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18184252801 + 9939292416 = 134849^2 + 99696^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28123545217 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 28123545217.

It is not a weakly prime, because it can be changed into another prime (28123545017) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14061772608 + 14061772609.

It is an arithmetic number, because the mean of its divisors is an integer number (14061772609).

Almost surely, 2^28123545217 is an apocalyptic number.

It is an amenable number.

28123545217 is a deficient number, since it is larger than the sum of its proper divisors (1).

28123545217 is an equidigital number, since it uses as much as digits as its factorization.

28123545217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 134400, while the sum is 40.

The spelling of 28123545217 in words is "twenty-eight billion, one hundred twenty-three million, five hundred forty-five thousand, two hundred seventeen".