25661605 has 4 divisors (see below), whose sum is σ = 30793932. Its totient is φ = 20529280.

The previous prime is 25661569. The next prime is 25661611. The reversal of 25661605 is 50616652.

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 13264164 + 12397441 = 3642^2 + 3521^2 .

It is not a de Polignac number, because 25661605 - 2⁹ = 25661093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2566156 + ... + 2566165.

It is an arithmetic number, because the mean of its divisors is an integer number (7698483).

Almost surely, 2^25661605 is an apocalyptic number.

It is an amenable number.

25661605 is a deficient number, since it is larger than the sum of its proper divisors (5132327).

25661605 is an equidigital number, since it uses as much as digits as its factorization.

25661605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5132326.

The product of its (nonzero) digits is 10800, while the sum is 31.

The square root of 25661605 is about 5065.7284767346. The cubic root of 25661605 is about 294.9587417163.

The spelling of 25661605 in words is "twenty-five million, six hundred sixty-one thousand, six hundred five".