25561440 has 192 divisors, whose sum is σ = 91869120. Its totient is φ = 6635520.

The previous prime is 25561439. The next prime is 25561447. The reversal of 25561440 is 4416552.

25561440 is a `hidden beast` number, since 2 + 5 + 5 + 614 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25561447) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 263472 + ... + 263568.

It is an arithmetic number, because the mean of its divisors is an integer number (478485).

Almost surely, 2^25561440 is an apocalyptic number.

25561440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 25561440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45934560).

25561440 is an abundant number, since it is smaller than the sum of its proper divisors (66307680).

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

25561440 is a wasteful number, since it uses less digits than its factorization.

25561440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 182 (or 168 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

The square root of 25561440 is about 5055.8322756990. The cubic root of 25561440 is about 294.5744702679.

Adding to 25561440 its reverse (4416552), we get a palindrome (29977992).

The spelling of 25561440 in words is "twenty-five million, five hundred sixty-one thousand, four hundred forty".