25209840 has 80 divisors (see below), whose sum is σ = 81566208. Its totient is φ = 6428928.

The previous prime is 25209829. The next prime is 25209859. The reversal of 25209840 is 4890252.

It is a tau number, because it is divible by the number of its divisors (80).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 25209798 and 25209807.

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 3237 + ... + 7803.

Almost surely, 2^25209840 is an apocalyptic number.

25209840 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 25209840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40783104).

25209840 is an abundant number, since it is smaller than the sum of its proper divisors (56356368).

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

25209840 is a wasteful number, since it uses less digits than its factorization.

25209840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4606 (or 4600 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 30.

The square root of 25209840 is about 5020.9401510076. The cubic root of 25209840 is about 293.2175966737.

The spelling of 25209840 in words is "twenty-five million, two hundred nine thousand, eight hundred forty".