25643440 has 40 divisors (see below), whose sum is σ = 60451488. Its totient is φ = 10114560.

The previous prime is 25643419. The next prime is 25643441. The reversal of 25643440 is 4434652.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 25643399 and 25643408.

It is not an unprimeable number, because it can be changed into a prime (25643441) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3645 + ... + 8035.

Almost surely, 2^25643440 is an apocalyptic number.

25643440 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 25643440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30225744).

25643440 is an abundant number, since it is smaller than the sum of its proper divisors (34808048).

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

25643440 is a wasteful number, since it uses less digits than its factorization.

25643440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4477 (or 4471 counting only the distinct ones).

The product of its (nonzero) digits is 11520, while the sum is 28.

The square root of 25643440 is about 5063.9352286537. The cubic root of 25643440 is about 294.8891281143.

The spelling of 25643440 in words is "twenty-five million, six hundred forty-three thousand, four hundred forty".