2686665666521 has 2 divisors, whose sum is σ = 2686665666522. Its totient is φ = 2686665666520.

The previous prime is 2686665666473. The next prime is 2686665666541. The reversal of 2686665666521 is 1256665666862.

2686665666521 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2681095134025 + 5570532496 = 1637405^2 + 74636^2 .

It is a cyclic number.

It is not a de Polignac number, because 2686665666521 - 2³⁴ = 2669485797337 is a prime.

It is not a weakly prime, because it can be changed into another prime (2686665666541) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1343332833260 + 1343332833261.

It is an arithmetic number, because the mean of its divisors is an integer number (1343332833261).

Almost surely, 2^{2686665666521} is an apocalyptic number.

It is an amenable number.

2686665666521 is a deficient number, since it is larger than the sum of its proper divisors (1).

2686665666521 is an equidigital number, since it uses as much as digits as its factorization.

2686665666521 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 223948800, while the sum is 65.

The spelling of 2686665666521 in words is "two trillion, six hundred eighty-six billion, six hundred sixty-five million, six hundred sixty-six thousand, five hundred twenty-one".