261613255691 has 2 divisors, whose sum is σ = 261613255692. Its totient is φ = 261613255690.

The previous prime is 261613255613. The next prime is 261613255727. The reversal of 261613255691 is 196552316162.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261613255691 is a prime.

It is not a weakly prime, because it can be changed into another prime (261613255291) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130806627845 + 130806627846.

It is an arithmetic number, because the mean of its divisors is an integer number (130806627846).

Almost surely, 2^261613255691 is an apocalyptic number.

261613255691 is a deficient number, since it is larger than the sum of its proper divisors (1).

261613255691 is an equidigital number, since it uses as much as digits as its factorization.

261613255691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 583200, while the sum is 47.

The spelling of 261613255691 in words is "two hundred sixty-one billion, six hundred thirteen million, two hundred fifty-five thousand, six hundred ninety-one".