28123545221 has 2 divisors, whose sum is σ = 28123545222. Its totient is φ = 28123545220.

The previous prime is 28123545217. The next prime is 28123545223. The reversal of 28123545221 is 12254532182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28118594596 + 4950625 = 167686^2 + 2225^2 .

It is a cyclic number.

It is not a de Polignac number, because 28123545221 - 2² = 28123545217 is a prime.

Together with 28123545223, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28123545223) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14061772610 + 14061772611.

It is an arithmetic number, because the mean of its divisors is an integer number (14061772611).

Almost surely, 2^28123545221 is an apocalyptic number.

It is an amenable number.

28123545221 is a deficient number, since it is larger than the sum of its proper divisors (1).

28123545221 is an equidigital number, since it uses as much as digits as its factorization.

28123545221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38400, while the sum is 35.

The spelling of 28123545221 in words is "twenty-eight billion, one hundred twenty-three million, five hundred forty-five thousand, two hundred twenty-one".