25664507640 has 256 divisors, whose sum is σ = 95349312000. Its totient is φ = 6102190080.

The previous prime is 25664507587. The next prime is 25664507647. The reversal of 25664507640 is 4670546652.

25664507640 is a `hidden beast` number, since 2 + 566 + 45 + 0 + 7 + 6 + 40 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25664507647) 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, 312055 + ... + 385625.

It is an arithmetic number, because the mean of its divisors is an integer number (372458250).

Almost surely, 2^25664507640 is an apocalyptic number.

25664507640 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 25664507640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (47674656000).

25664507640 is an abundant number, since it is smaller than the sum of its proper divisors (69684804360).

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

25664507640 is a wasteful number, since it uses less digits than its factorization.

25664507640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73627 (or 73617 counting only the distinct ones).

The product of its (nonzero) digits is 1209600, while the sum is 45.

The spelling of 25664507640 in words is "twenty-five billion, six hundred sixty-four million, five hundred seven thousand, six hundred forty".