25661729280 has 640 divisors, whose sum is σ = 95712731136. Its totient is φ = 5803212800.

The previous prime is 25661729267. The next prime is 25661729299. The reversal of 25661729280 is 8292716652.

It is a tau number, because it is divible by the number of its divisors (640).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 91322740 + ... + 91323020.

Almost surely, 2^25661729280 is an apocalyptic number.

25661729280 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 25661729280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47856365568).

25661729280 is an abundant number, since it is smaller than the sum of its proper divisors (70051001856).

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

25661729280 is a wasteful number, since it uses less digits than its factorization.

25661729280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388 (or 372 counting only the distinct ones).

The product of its (nonzero) digits is 725760, while the sum is 48.

The spelling of 25661729280 in words is "twenty-five billion, six hundred sixty-one million, seven hundred twenty-nine thousand, two hundred eighty".