261805520663 has 2 divisors, whose sum is σ = 261805520664. Its totient is φ = 261805520662.

The previous prime is 261805520653. The next prime is 261805520729. The reversal of 261805520663 is 366025508162.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261805520663 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261805520653) by changing a digit.

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 as a sum of consecutive naturals, namely, 130902760331 + 130902760332.

It is an arithmetic number, because the mean of its divisors is an integer number (130902760332).

Almost surely, 2^261805520663 is an apocalyptic number.

261805520663 is a deficient number, since it is larger than the sum of its proper divisors (1).

261805520663 is an equidigital number, since it uses as much as digits as its factorization.

261805520663 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 518400, while the sum is 44.

The spelling of 261805520663 in words is "two hundred sixty-one billion, eight hundred five million, five hundred twenty thousand, six hundred sixty-three".