25661742010565 has 32 divisors (see below), whose sum is σ = 31239341733600. Its totient is φ = 20234696417280.

The previous prime is 25661742010549. The next prime is 25661742010591. The reversal of 25661742010565 is 56501024716652.

It is a Cunningham number, because it is equal to 5065742²+1.

It can be written as a sum of positive squares in 16 ways, for example, as 13662182745121 + 11999559265444 = 3696239^2 + 3464038^2 .

It is not a de Polignac number, because 25661742010565 - 2⁴ = 25661742010549 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 135652445 + ... + 135841485.

It is an arithmetic number, because the mean of its divisors is an integer number (976229429175).

Almost surely, 2^{25661742010565} is an apocalyptic number.

It is an amenable number.

25661742010565 is a deficient number, since it is larger than the sum of its proper divisors (5577599723035).

25661742010565 is a wasteful number, since it uses less digits than its factorization.

25661742010565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190457.

The product of its (nonzero) digits is 3024000, while the sum is 50.

The spelling of 25661742010565 in words is "twenty-five trillion, six hundred sixty-one billion, seven hundred forty-two million, ten thousand, five hundred sixty-five".