261161128881780 has 24 divisors (see below), whose sum is σ = 731251160869152. Its totient is φ = 69642967701792.

The previous prime is 261161128881767. The next prime is 261161128881817. The reversal of 261161128881780 is 87188821161162.

It is a Harshad number since it is a multiple of its sum of digits (60), and also a Moran number because the ratio is a prime number: 4352685481363 = 261161128881780 / (2 + 6 + 1 + 1 + 6 + 1 + 1 + 2 + 8 + 8 + 8 + 1 + 7 + 8 + 0).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2176342740622 + ... + 2176342740741.

It is an arithmetic number, because the mean of its divisors is an integer number (30468798369548).

Almost surely, 2^{261161128881780} is an apocalyptic number.

261161128881780 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261161128881780 is an abundant number, since it is smaller than the sum of its proper divisors (470090031987372).

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

261161128881780 is a wasteful number, since it uses less digits than its factorization.

261161128881780 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4352685481375 (or 4352685481373 counting only the distinct ones).

The product of its (nonzero) digits is 4128768, while the sum is 60.

The spelling of 261161128881780 in words is "two hundred sixty-one trillion, one hundred sixty-one billion, one hundred twenty-eight million, eight hundred eighty-one thousand, seven hundred eighty".