261083664847781 has 2 divisors, whose sum is σ = 261083664847782. Its totient is φ = 261083664847780.

The previous prime is 261083664847727. The next prime is 261083664847867. The reversal of 261083664847781 is 187748466380162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 211446933676225 + 49636731171556 = 14541215^2 + 7045334^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-261083664847781 is a prime.

It is a super-2 number, since 2×261083664847781² (a number of 30 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261083664841781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130541832423890 + 130541832423891.

It is an arithmetic number, because the mean of its divisors is an integer number (130541832423891).

Almost surely, 2^{261083664847781} is an apocalyptic number.

It is an amenable number.

261083664847781 is a deficient number, since it is larger than the sum of its proper divisors (1).

261083664847781 is an equidigital number, since it uses as much as digits as its factorization.

261083664847781 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 520224768, while the sum is 71.

The spelling of 261083664847781 in words is "two hundred sixty-one trillion, eighty-three billion, six hundred sixty-four million, eight hundred forty-seven thousand, seven hundred eighty-one".