25855642581 has 4 divisors (see below), whose sum is σ = 34474190112. Its totient is φ = 17237095052.

The previous prime is 25855642577. The next prime is 25855642621. The reversal of 25855642581 is 18524655852.

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 25855642581 - 2² = 25855642577 is a prime.

It is a super-2 number, since 2×25855642581² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25855642181) 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, 4309273761 + ... + 4309273766.

It is an arithmetic number, because the mean of its divisors is an integer number (8618547528).

Almost surely, 2^25855642581 is an apocalyptic number.

It is an amenable number.

25855642581 is a deficient number, since it is larger than the sum of its proper divisors (8618547531).

25855642581 is an equidigital number, since it uses as much as digits as its factorization.

25855642581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8618547530.

The product of its digits is 3840000, while the sum is 51.

The spelling of 25855642581 in words is "twenty-five billion, eight hundred fifty-five million, six hundred forty-two thousand, five hundred eighty-one".