261181497780 has 288 divisors, whose sum is σ = 953724844800. Its totient is φ = 56518539264.

The previous prime is 261181497769. The next prime is 261181497847. The reversal of 261181497780 is 87794181162.

261181497780 is a `hidden beast` number, since 2 + 6 + 1 + 1 + 81 + 497 + 78 + 0 = 666.

261181497780 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 49529224 + ... + 49534496.

It is an arithmetic number, because the mean of its divisors is an integer number (3311544600).

Almost surely, 2^261181497780 is an apocalyptic number.

261181497780 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 261181497780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (476862422400).

261181497780 is an abundant number, since it is smaller than the sum of its proper divisors (692543347020).

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

261181497780 is a wasteful number, since it uses less digits than its factorization.

261181497780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7383 (or 7378 counting only the distinct ones).

The product of its (nonzero) digits is 1354752, while the sum is 54.

The spelling of 261181497780 in words is "two hundred sixty-one billion, one hundred eighty-one million, four hundred ninety-seven thousand, seven hundred eighty".