28173128261 has 2 divisors, whose sum is σ = 28173128262. Its totient is φ = 28173128260.

The previous prime is 28173128201. The next prime is 28173128273. The reversal of 28173128261 is 16282137182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23105824036 + 5067304225 = 152006^2 + 71185^2 .

It is a cyclic number.

It is not a de Polignac number, because 28173128261 - 2³⁰ = 27099386437 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28173128201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14086564130 + 14086564131.

It is an arithmetic number, because the mean of its divisors is an integer number (14086564131).

Almost surely, 2^28173128261 is an apocalyptic number.

It is an amenable number.

28173128261 is a deficient number, since it is larger than the sum of its proper divisors (1).

28173128261 is an equidigital number, since it uses as much as digits as its factorization.

28173128261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 64512, while the sum is 41.

The spelling of 28173128261 in words is "twenty-eight billion, one hundred seventy-three million, one hundred twenty-eight thousand, two hundred sixty-one".