25805561 has 4 divisors (see below), whose sum is σ = 25908624. Its totient is φ = 25702500.

The previous prime is 25805543. The next prime is 25805567. The reversal of 25805561 is 16550852.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 25805561 - 2⁶ = 25805497 is a prime.

It is a super-3 number, since 3×25805561³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25805567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51155 + ... + 51656.

It is an arithmetic number, because the mean of its divisors is an integer number (6477156).

Almost surely, 2^25805561 is an apocalyptic number.

It is an amenable number.

25805561 is a deficient number, since it is larger than the sum of its proper divisors (103063).

25805561 is a wasteful number, since it uses less digits than its factorization.

25805561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103062.

The product of its (nonzero) digits is 12000, while the sum is 32.

The square root of 25805561 is about 5079.9174205886. The cubic root of 25805561 is about 295.5092649334.

The spelling of 25805561 in words is "twenty-five million, eight hundred five thousand, five hundred sixty-one".