25521021008 has 80 divisors (see below), whose sum is σ = 59546903040. Its totient is φ = 10351152000.

The previous prime is 25521020999. The next prime is 25521021013. The reversal of 25521021008 is 80012012552.

It is a Cunningham number, because it is equal to 159753²-1.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2230823 + ... + 2242233.

It is an arithmetic number, because the mean of its divisors is an integer number (744336288).

Almost surely, 2^25521021008 is an apocalyptic number.

25521021008 is a gapful number since it is divisible by the number (28) 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 25521021008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29773451520).

25521021008 is an abundant number, since it is smaller than the sum of its proper divisors (34025882032).

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

25521021008 is a wasteful number, since it uses less digits than its factorization.

25521021008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12496 (or 12490 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 26.

The spelling of 25521021008 in words is "twenty-five billion, five hundred twenty-one million, twenty-one thousand, eight".