261665651514643 has 2 divisors, whose sum is σ = 261665651514644. Its totient is φ = 261665651514642.

The previous prime is 261665651514581. The next prime is 261665651514713. The reversal of 261665651514643 is 346415156566162.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 261665651514643 - 2¹³ = 261665651506451 is a prime.

It is not a weakly prime, because it can be changed into another prime (261665651511643) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130832825757321 + 130832825757322.

It is an arithmetic number, because the mean of its divisors is an integer number (130832825757322).

Almost surely, 2^{261665651514643} is an apocalyptic number.

261665651514643 is a deficient number, since it is larger than the sum of its proper divisors (1).

261665651514643 is an equidigital number, since it uses as much as digits as its factorization.

261665651514643 is an evil number, because the sum of its binary digits is even.

The product of its digits is 93312000, while the sum is 61.

The spelling of 261665651514643 in words is "two hundred sixty-one trillion, six hundred sixty-five billion, six hundred fifty-one million, five hundred fourteen thousand, six hundred forty-three".