25643266640 has 20 divisors (see below), whose sum is σ = 59620595124. Its totient is φ = 10257306624.

The previous prime is 25643266613. The next prime is 25643266679. The reversal of 25643266640 is 4666234652.

It can be written as a sum of positive squares in 2 ways, for example, as 6117116944 + 19526149696 = 78212^2 + 139736^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a junction number, because it is equal to n+sod(n) for n = 25643266591 and 25643266600.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 160270337 + ... + 160270496.

Almost surely, 2^25643266640 is an apocalyptic number.

25643266640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

25643266640 is an abundant number, since it is smaller than the sum of its proper divisors (33977328484).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

25643266640 is a wasteful number, since it uses less digits than its factorization.

25643266640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320540846 (or 320540840 counting only the distinct ones).

The product of its (nonzero) digits is 1244160, while the sum is 44.

The spelling of 25643266640 in words is "twenty-five billion, six hundred forty-three million, two hundred sixty-six thousand, six hundred forty".