256611502542640 has 320 divisors, whose sum is σ = 718254993309696. Its totient is φ = 83356985834496.

The previous prime is 256611502542607. The next prime is 256611502542643. The reversal of 256611502542640 is 46245205116652.

It is not an unprimeable number, because it can be changed into a prime (256611502542643) 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, 16404230659 + ... + 16404246301.

Almost surely, 2^{256611502542640} is an apocalyptic number.

256611502542640 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 256611502542640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (359127496654848).

256611502542640 is an abundant number, since it is smaller than the sum of its proper divisors (461643490767056).

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

256611502542640 is a wasteful number, since it uses less digits than its factorization.

256611502542640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27696 (or 27690 counting only the distinct ones).

The product of its (nonzero) digits is 3456000, while the sum is 49.

The spelling of 256611502542640 in words is "two hundred fifty-six trillion, six hundred eleven billion, five hundred two million, five hundred forty-two thousand, six hundred forty".