261728935649 has 8 divisors (see below), whose sum is σ = 263829444840. Its totient is φ = 259636779136.

The previous prime is 261728935609. The next prime is 261728935667. The reversal of 261728935649 is 946539827162.

261728935649 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 18736134400 + 242992801249 = 136880^2 + 492943^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261728935649 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 261728935591 and 261728935600.

It is not an unprimeable number, because it can be changed into a prime (261728935609) 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 7 ways as a sum of consecutive naturals, for example, 2025242 + ... + 2150595.

It is an arithmetic number, because the mean of its divisors is an integer number (32978680605).

Almost surely, 2^261728935649 is an apocalyptic number.

It is an amenable number.

261728935649 is a deficient number, since it is larger than the sum of its proper divisors (2100509191).

261728935649 is a wasteful number, since it uses less digits than its factorization.

261728935649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4176339.

The product of its digits is 39191040, while the sum is 62.

The spelling of 261728935649 in words is "two hundred sixty-one billion, seven hundred twenty-eight million, nine hundred thirty-five thousand, six hundred forty-nine".