261206539776 has 480 divisors, whose sum is σ = 962233079808. Its totient is φ = 68886650880.

The previous prime is 261206539753. The next prime is 261206539777. The reversal of 261206539776 is 677935602162.

261206539776 is a `hidden beast` number, since 2 + 6 + 120 + 65 + 397 + 76 = 666.

261206539776 is digitally balanced in base 2, 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 a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261206539777) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 11310321 + ... + 11333391.

Almost surely, 2^261206539776 is an apocalyptic number.

261206539776 is a gapful number since it is divisible by the number (26) 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 261206539776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (481116539904).

261206539776 is an abundant number, since it is smaller than the sum of its proper divisors (701026540032).

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

261206539776 is an equidigital number, since it uses as much as digits as its factorization.

261206539776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23124 (or 23096 counting only the distinct ones).

The product of its (nonzero) digits is 5715360, while the sum is 54.

The spelling of 261206539776 in words is "two hundred sixty-one billion, two hundred six million, five hundred thirty-nine thousand, seven hundred seventy-six".