25521640704 has 864 divisors, whose sum is σ = 94281707520. Its totient is φ = 6730407936.

The previous prime is 25521640691. The next prime is 25521640709. The reversal of 25521640704 is 40704612552.

It is a happy number.

25521640704 is a `hidden beast` number, since 2 + 5 + 5 + 2 + 1 + 640 + 7 + 0 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (864).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25521640709) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 543013609 + ... + 543013655.

Almost surely, 2^25521640704 is an apocalyptic number.

25521640704 is a gapful number since it is divisible by the number (24) 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 25521640704, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47140853760).

25521640704 is an abundant number, since it is smaller than the sum of its proper divisors (68760066816).

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

25521640704 is an equidigital number, since it uses as much as digits as its factorization.

25521640704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 157 (or 131 counting only the distinct ones).

The product of its (nonzero) digits is 67200, while the sum is 36.

The spelling of 25521640704 in words is "twenty-five billion, five hundred twenty-one million, six hundred forty thousand, seven hundred four".