261440351568 has 640 divisors, whose sum is σ = 873658368000. Its totient is φ = 74114611200.

The previous prime is 261440351563. The next prime is 261440351597. The reversal of 261440351568 is 865153044162.

261440351568 is a `hidden beast` number, since 2 + 6 + 14 + 40 + 35 + 1 + 568 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261440351563) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 943827846 + ... + 943828122.

It is an arithmetic number, because the mean of its divisors is an integer number (1365091200).

Almost surely, 2^261440351568 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261440351568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (436829184000).

261440351568 is an abundant number, since it is smaller than the sum of its proper divisors (612218016432).

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

261440351568 is a wasteful number, since it uses less digits than its factorization.

261440351568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 528 (or 516 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 45.

The spelling of 261440351568 in words is "two hundred sixty-one billion, four hundred forty million, three hundred fifty-one thousand, five hundred sixty-eight".