255638384640 has 520 divisors, whose sum is σ = 929392535808. Its totient is φ = 67204546560.

The previous prime is 255638384633. The next prime is 255638384641. The reversal of 255638384640 is 46483836552.

255638384640 is a `hidden beast` number, since 2 + 5 + 563 + 8 + 38 + 4 + 6 + 40 = 666.

255638384640 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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 (255638384641) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 121097185 + ... + 121099295.

Almost surely, 2^255638384640 is an apocalyptic number.

255638384640 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 255638384640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (464696267904).

255638384640 is an abundant number, since it is smaller than the sum of its proper divisors (673754151168).

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

255638384640 is an equidigital number, since it uses as much as digits as its factorization.

255638384640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2225 (or 2194 counting only the distinct ones).

The product of its (nonzero) digits is 16588800, while the sum is 54.

The spelling of 255638384640 in words is "two hundred fifty-five billion, six hundred thirty-eight million, three hundred eighty-four thousand, six hundred forty".