25805528561 has 4 divisors (see below), whose sum is σ = 25948100724. Its totient is φ = 25662956400.

The previous prime is 25805528549. The next prime is 25805528587. The reversal of 25805528561 is 16582550852.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7302727936 + 18502800625 = 85456^2 + 136025^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25805528561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25805528521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71285810 + ... + 71286171.

It is an arithmetic number, because the mean of its divisors is an integer number (6487025181).

Almost surely, 2^25805528561 is an apocalyptic number.

It is an amenable number.

25805528561 is a deficient number, since it is larger than the sum of its proper divisors (142572163).

25805528561 is a wasteful number, since it uses less digits than its factorization.

25805528561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142572162.

The product of its (nonzero) digits is 960000, while the sum is 47.

The spelling of 25805528561 in words is "twenty-five billion, eight hundred five million, five hundred twenty-eight thousand, five hundred sixty-one".