261551107678361 has 2 divisors, whose sum is σ = 261551107678362. Its totient is φ = 261551107678360.

The previous prime is 261551107678331. The next prime is 261551107678373. The reversal of 261551107678361 is 163876701155162.

261551107678361 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 173904063678361 + 87647044000000 = 13187269^2 + 9362000^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261551107678361 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 261551107678361.

It is not a weakly prime, because it can be changed into another prime (261551107678331) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130775553839180 + 130775553839181.

It is an arithmetic number, because the mean of its divisors is an integer number (130775553839181).

Almost surely, 2^{261551107678361} is an apocalyptic number.

It is an amenable number.

261551107678361 is a deficient number, since it is larger than the sum of its proper divisors (1).

261551107678361 is an equidigital number, since it uses as much as digits as its factorization.

261551107678361 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12700800, while the sum is 59.

The spelling of 261551107678361 in words is "two hundred sixty-one trillion, five hundred fifty-one billion, one hundred seven million, six hundred seventy-eight thousand, three hundred sixty-one".