25440 has 48 divisors (see below), whose sum is σ = 81648. Its totient is φ = 6656.

The previous prime is 25439. The next prime is 25447. The reversal of 25440 is 4452.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 25440.

It is not an unprimeable number, because it can be changed into a prime (25447) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 454 + ... + 506.

It is an arithmetic number, because the mean of its divisors is an integer number (1701).

2²⁵⁴⁴⁰ is an apocalyptic number.

25440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is a pronic number, being equal to 159×160.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 25440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40824).

25440 is an abundant number, since it is smaller than the sum of its proper divisors (56208).

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

25440 is a wasteful number, since it uses less digits than its factorization.

25440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71 (or 63 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 15.

The square root of 25440 is about 159.4992162990. The cubic root of 25440 is about 29.4107231004.

Subtracting from 25440 its sum of digits (15), we obtain a triangular number (25425 = T₂₂₅).

Adding to 25440 its product of nonzero digits (160), we get a square (25600 = 160²).

Adding to 25440 its reverse (4452), we get a palindrome (29892).

It can be divided in two parts, 25 and 440, that added together give a triangular number (465 = T₃₀).

The spelling of 25440 in words is "twenty-five thousand, four hundred forty".