25809166656 has 336 divisors, whose sum is σ = 94194172800. Its totient is φ = 6571708416.

The previous prime is 25809166637. The next prime is 25809166687. The reversal of 25809166656 is 65666190852.

It is a tau number, because it is divible by the number of its divisors (336).

It is a super-2 number, since 2×25809166656² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1511575 + ... + 1528553.

It is an arithmetic number, because the mean of its divisors is an integer number (280339800).

Almost surely, 2^25809166656 is an apocalyptic number.

25809166656 is a gapful number since it is divisible by the number (26) 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 25809166656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47097086400).

25809166656 is an abundant number, since it is smaller than the sum of its proper divisors (68385006144).

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

25809166656 is a wasteful number, since it uses less digits than its factorization.

25809166656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17046 (or 17033 counting only the distinct ones).

The product of its (nonzero) digits is 4665600, while the sum is 54.

The spelling of 25809166656 in words is "twenty-five billion, eight hundred nine million, one hundred sixty-six thousand, six hundred fifty-six".