261894560256 has 1440 divisors, whose sum is σ = 1021490870400. Its totient is φ = 66718826496.

The previous prime is 261894560243. The next prime is 261894560261. The reversal of 261894560256 is 652065498162.

261894560256 is a `hidden beast` number, since 2 + 6 + 189 + 456 + 0 + 2 + 5 + 6 = 666.

It is a super-2 number, since 2×261894560256² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 13783924215 + ... + 13783924233.

It is an arithmetic number, because the mean of its divisors is an integer number (709368660).

Almost surely, 2^261894560256 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 261894560256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (510745435200).

261894560256 is an abundant number, since it is smaller than the sum of its proper divisors (759596310144).

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

261894560256 is an frugal number, since it uses more digits than its factorization.

261894560256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109 (or 48 counting only the distinct ones).

The product of its (nonzero) digits is 6220800, while the sum is 54.

The spelling of 261894560256 in words is "two hundred sixty-one billion, eight hundred ninety-four million, five hundred sixty thousand, two hundred fifty-six".