25766642781 has 84 divisors (see below), whose sum is σ = 43192037280. Its totient is φ = 15348366000.

The previous prime is 25766642771. The next prime is 25766642801. The reversal of 25766642781 is 18724666752.

It is a happy number.

It is not a de Polignac number, because 25766642781 - 2⁵ = 25766642749 is a prime.

It is a super-2 number, since 2×25766642781² (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 (25766642701) by changing a digit.

It is a polite number, since it can be written in 83 ways as a sum of consecutive naturals, for example, 5201856 + ... + 5206806.

It is an arithmetic number, because the mean of its divisors is an integer number (514190920).

Almost surely, 2^25766642781 is an apocalyptic number.

It is an amenable number.

25766642781 is a deficient number, since it is larger than the sum of its proper divisors (17425394499).

25766642781 is an equidigital number, since it uses as much as digits as its factorization.

25766642781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5050 (or 5024 counting only the distinct ones).

The product of its digits is 6773760, while the sum is 54.

The spelling of 25766642781 in words is "twenty-five billion, seven hundred sixty-six million, six hundred forty-two thousand, seven hundred eighty-one".