261665573346577 has 2 divisors, whose sum is σ = 261665573346578. Its totient is φ = 261665573346576.

The previous prime is 261665573346547. The next prime is 261665573346679. The reversal of 261665573346577 is 775643375566162.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 232125000451201 + 29540572895376 = 15235649^2 + 5435124^2 .

It is a cyclic number.

It is not a de Polignac number, because 261665573346577 - 2³⁵ = 261631213608209 is a prime.

It is not a weakly prime, because it can be changed into another prime (261665573346547) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130832786673288 + 130832786673289.

It is an arithmetic number, because the mean of its divisors is an integer number (130832786673289).

Almost surely, 2^{261665573346577} is an apocalyptic number.

It is an amenable number.

261665573346577 is a deficient number, since it is larger than the sum of its proper divisors (1).

261665573346577 is an equidigital number, since it uses as much as digits as its factorization.

261665573346577 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4000752000, while the sum is 73.

The spelling of 261665573346577 in words is "two hundred sixty-one trillion, six hundred sixty-five billion, five hundred seventy-three million, three hundred forty-six thousand, five hundred seventy-seven".