25661645856 has 384 divisors, whose sum is σ = 93623040000. Its totient is φ = 6643399680.

The previous prime is 25661645851. The next prime is 25661645921. The reversal of 25661645856 is 65854616652.

25661645856 is a `hidden beast` number, since 2 + 56 + 6 + 1 + 6 + 4 + 585 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (25661645851) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 33197086 + ... + 33197858.

It is an arithmetic number, because the mean of its divisors is an integer number (243810000).

Almost surely, 2^25661645856 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 25661645856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (46811520000).

25661645856 is an abundant number, since it is smaller than the sum of its proper divisors (67961394144).

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

25661645856 is a wasteful number, since it uses less digits than its factorization.

25661645856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1309 (or 1295 counting only the distinct ones).

The product of its digits is 10368000, while the sum is 54.

The spelling of 25661645856 in words is "twenty-five billion, six hundred sixty-one million, six hundred forty-five thousand, eight hundred fifty-six".