257812505640 has 320 divisors, whose sum is σ = 895755294720. Its totient is φ = 66507350400.

The previous prime is 257812505633. The next prime is 257812505641. The reversal of 257812505640 is 46505218752.

257812505640 is a `hidden beast` number, since 2 + 5 + 7 + 81 + 2 + 5 + 0 + 564 + 0 = 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 (257812505641) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 96521505 + ... + 96524175.

It is an arithmetic number, because the mean of its divisors is an integer number (2799235296).

Almost surely, 2^257812505640 is an apocalyptic number.

257812505640 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 257812505640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (447877647360).

257812505640 is an abundant number, since it is smaller than the sum of its proper divisors (637942789080).

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

257812505640 is an equidigital number, since it uses as much as digits as its factorization.

257812505640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2787 (or 2712 counting only the distinct ones).

The product of its (nonzero) digits is 672000, while the sum is 45.

The spelling of 257812505640 in words is "two hundred fifty-seven billion, eight hundred twelve million, five hundred five thousand, six hundred forty".