25685867781 has 12 divisors (see below), whose sum is σ = 42402067552. Its totient is φ = 14677638696.

The previous prime is 25685867777. The next prime is 25685867789. The reversal of 25685867781 is 18776858652.

25685867781 is a `hidden beast` number, since 2 + 568 + 5 + 8 + 67 + 7 + 8 + 1 = 666.

It is not a de Polignac number, because 25685867781 - 2² = 25685867777 is a prime.

It is a super-2 number, since 2×25685867781² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63), and also a Moran number because the ratio is a prime number: 407712187 = 25685867781 / (2 + 5 + 6 + 8 + 5 + 8 + 6 + 7 + 7 + 8 + 1).

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25685867789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 203856031 + ... + 203856156.

Almost surely, 2^25685867781 is an apocalyptic number.

25685867781 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

25685867781 is a deficient number, since it is larger than the sum of its proper divisors (16716199771).

25685867781 is a wasteful number, since it uses less digits than its factorization.

25685867781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 407712200 (or 407712197 counting only the distinct ones).

The product of its digits is 45158400, while the sum is 63.

The spelling of 25685867781 in words is "twenty-five billion, six hundred eighty-five million, eight hundred sixty-seven thousand, seven hundred eighty-one".