25566500161 has 2 divisors, whose sum is σ = 25566500162. Its totient is φ = 25566500160.

The previous prime is 25566500131. The next prime is 25566500173. The reversal of 25566500161 is 16100566552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 24926410161 + 640090000 = 157881^2 + 25300^2 .

It is a cyclic number.

It is not a de Polignac number, because 25566500161 - 2⁵ = 25566500129 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 25566500161.

It is not a weakly prime, because it can be changed into another prime (25566500131) 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, 12783250080 + 12783250081.

It is an arithmetic number, because the mean of its divisors is an integer number (12783250081).

Almost surely, 2^25566500161 is an apocalyptic number.

It is an amenable number.

25566500161 is a deficient number, since it is larger than the sum of its proper divisors (1).

25566500161 is an equidigital number, since it uses as much as digits as its factorization.

25566500161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54000, while the sum is 37.

The spelling of 25566500161 in words is "twenty-five billion, five hundred sixty-six million, five hundred thousand, one hundred sixty-one".