261665573346493 has 2 divisors, whose sum is σ = 261665573346494. Its totient is φ = 261665573346492.

The previous prime is 261665573346473. The next prime is 261665573346511. The reversal of 261665573346493 is 394643375566162.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 258559389167524 + 3106184178969 = 16079782^2 + 1762437^2 .

It is a cyclic number.

It is not a de Polignac number, because 261665573346493 - 2⁵ = 261665573346461 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261665573346403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130832786673246 + 130832786673247.

It is an arithmetic number, because the mean of its divisors is an integer number (130832786673247).

Almost surely, 2^{261665573346493} is an apocalyptic number.

It is an amenable number.

261665573346493 is a deficient number, since it is larger than the sum of its proper divisors (1).

261665573346493 is an equidigital number, since it uses as much as digits as its factorization.

261665573346493 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1763596800, while the sum is 70.

The spelling of 261665573346493 in words is "two hundred sixty-one trillion, six hundred sixty-five billion, five hundred seventy-three million, three hundred forty-six thousand, four hundred ninety-three".