1720661260817 has 2 divisors, whose sum is σ = 1720661260818. Its totient is φ = 1720661260816.

The previous prime is 1720661260793. The next prime is 1720661260873. The reversal of 1720661260817 is 7180621660271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1150279845121 + 570381415696 = 1072511^2 + 755236^2 .

It is a cyclic number.

It is not a de Polignac number, because 1720661260817 - 2³⁰ = 1719587518993 is a prime.

It is not a weakly prime, because it can be changed into another prime (1720661260117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860330630408 + 860330630409.

It is an arithmetic number, because the mean of its divisors is an integer number (860330630409).

Almost surely, 2^{1720661260817} is an apocalyptic number.

It is an amenable number.

1720661260817 is a deficient number, since it is larger than the sum of its proper divisors (1).

1720661260817 is an equidigital number, since it uses as much as digits as its factorization.

1720661260817 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 338688, while the sum is 47.

The spelling of 1720661260817 in words is "one trillion, seven hundred twenty billion, six hundred sixty-one million, two hundred sixty thousand, eight hundred seventeen".