25661511655560 has 384 divisors, whose sum is σ = 91642286736000. Its totient is φ = 6175851601920.

The previous prime is 25661511655519. The next prime is 25661511655583. The reversal of 25661511655560 is 6555611516652.

25661511655560 is a `hidden beast` number, since 2 + 5 + 6 + 6 + 1 + 5 + 11 + 65 + 5 + 560 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 25661511655497 and 25661511655506.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1181839264 + ... + 1181860976.

It is an arithmetic number, because the mean of its divisors is an integer number (238651788375).

Almost surely, 2^{25661511655560} is an apocalyptic number.

25661511655560 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 25661511655560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (45821143368000).

25661511655560 is an abundant number, since it is smaller than the sum of its proper divisors (65980775080440).

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

25661511655560 is a wasteful number, since it uses less digits than its factorization.

25661511655560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23893 (or 23886 counting only the distinct ones).

The product of its (nonzero) digits is 8100000, while the sum is 54.

The spelling of 25661511655560 in words is "twenty-five trillion, six hundred sixty-one billion, five hundred eleven million, six hundred fifty-five thousand, five hundred sixty".