25209640 has 64 divisors (see below), whose sum is σ = 60730560. Its totient is φ = 9384960.

The previous prime is 25209631. The next prime is 25209643. The reversal of 25209640 is 4690252.

It is a junction number, because it is equal to n+sod(n) for n = 25209599 and 25209608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25209643) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 88939 + ... + 89221.

It is an arithmetic number, because the mean of its divisors is an integer number (948915).

Almost surely, 2^25209640 is an apocalyptic number.

25209640 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 25209640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30365280).

25209640 is an abundant number, since it is smaller than the sum of its proper divisors (35520920).

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

25209640 is a wasteful number, since it uses less digits than its factorization.

25209640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 442 (or 438 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 25209640 is about 5020.9202343794. The cubic root of 25209640 is about 293.2168212665.

Adding to 25209640 its reverse (4690252), we get a palindrome (29899892).

The spelling of 25209640 in words is "twenty-five million, two hundred nine thousand, six hundred forty".