25808991 has 8 divisors (see below), whose sum is σ = 37059120. Its totient is φ = 15882432.

The previous prime is 25808977. The next prime is 25809029. The reversal of 25808991 is 19980852.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 25808991 - 2¹⁴ = 25792607 is a prime.

It is a super-2 number, since 2×25808991² = 1332208032876162, which contains 22 as substring.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25808291) 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 7 ways as a sum of consecutive naturals, for example, 330846 + ... + 330923.

It is an arithmetic number, because the mean of its divisors is an integer number (4632390).

Almost surely, 2^25808991 is an apocalyptic number.

25808991 is a deficient number, since it is larger than the sum of its proper divisors (11250129).

25808991 is a wasteful number, since it uses less digits than its factorization.

25808991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 661785.

The product of its (nonzero) digits is 51840, while the sum is 42.

The square root of 25808991 is about 5080.2550132843. The cubic root of 25808991 is about 295.5223570969.

The spelling of 25808991 in words is "twenty-five million, eight hundred eight thousand, nine hundred ninety-one".