25506721800 has 960 divisors, whose sum is σ = 109087482240. Its totient is φ = 5391360000.

The previous prime is 25506721781. The next prime is 25506721829. The reversal of 25506721800 is 812760552.

It is a happy number.

25506721800 is a `hidden beast` number, since 2 + 5 + 506 + 72 + 1 + 80 + 0 = 666.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 194707735 + ... + 194707865.

It is an arithmetic number, because the mean of its divisors is an integer number (113632794).

Almost surely, 2^25506721800 is an apocalyptic number.

25506721800 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 25506721800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (54543741120).

25506721800 is an abundant number, since it is smaller than the sum of its proper divisors (83580760440).

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

25506721800 is a wasteful number, since it uses less digits than its factorization.

25506721800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 284 (or 266 counting only the distinct ones).

The product of its (nonzero) digits is 33600, while the sum is 36.

The spelling of 25506721800 in words is "twenty-five billion, five hundred six million, seven hundred twenty-one thousand, eight hundred".