25781540 has 12 divisors (see below), whose sum is σ = 54141276. Its totient is φ = 10312608.

The previous prime is 25781531. The next prime is 25781557. The reversal of 25781540 is 4518752.

It can be written as a sum of positive squares in 2 ways, for example, as 15808576 + 9972964 = 3976^2 + 3158^2 .

It is a junction number, because it is equal to n+sod(n) for n = 25781497 and 25781506.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 644519 + ... + 644558.

It is an arithmetic number, because the mean of its divisors is an integer number (4511773).

Almost surely, 2^25781540 is an apocalyptic number.

25781540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

25781540 is an abundant number, since it is smaller than the sum of its proper divisors (28359736).

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

25781540 is a wasteful number, since it uses less digits than its factorization.

25781540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1289086 (or 1289084 counting only the distinct ones).

The product of its (nonzero) digits is 11200, while the sum is 32.

The square root of 25781540 is about 5077.5525600431. The cubic root of 25781540 is about 295.4175452752.

The spelling of 25781540 in words is "twenty-five million, seven hundred eighty-one thousand, five hundred forty".