1720785780001 has 2 divisors, whose sum is σ = 1720785780002. Its totient is φ = 1720785780000.

The previous prime is 1720785779983. The next prime is 1720785780023. The reversal of 1720785780001 is 1000875870271.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1323532901601 + 397252878400 = 1150449^2 + 630280^2 .

It is an emirp because it is prime and its reverse (1000875870271) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1720785780001 - 2¹⁹ = 1720785255713 is a prime.

It is a super-2 number, since 2×1720785780001² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1720785780101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860392890000 + 860392890001.

It is an arithmetic number, because the mean of its divisors is an integer number (860392890001).

Almost surely, 2^{1720785780001} is an apocalyptic number.

It is an amenable number.

1720785780001 is a deficient number, since it is larger than the sum of its proper divisors (1).

1720785780001 is an equidigital number, since it uses as much as digits as its factorization.

1720785780001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 219520, while the sum is 46.

The spelling of 1720785780001 in words is "one trillion, seven hundred twenty billion, seven hundred eighty-five million, seven hundred eighty thousand, one".