25555508221 has 2 divisors, whose sum is σ = 25555508222. Its totient is φ = 25555508220.

The previous prime is 25555508201. The next prime is 25555508227. The reversal of 25555508221 is 12280555552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14886684121 + 10668824100 = 122011^2 + 103290^2 .

It is a cyclic number.

It is not a de Polignac number, because 25555508221 - 2²⁵ = 25521953789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25555508227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12777754110 + 12777754111.

It is an arithmetic number, because the mean of its divisors is an integer number (12777754111).

Almost surely, 2^25555508221 is an apocalyptic number.

It is an amenable number.

25555508221 is a deficient number, since it is larger than the sum of its proper divisors (1).

25555508221 is an equidigital number, since it uses as much as digits as its factorization.

25555508221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 200000, while the sum is 40.

The spelling of 25555508221 in words is "twenty-five billion, five hundred fifty-five million, five hundred eight thousand, two hundred twenty-one".