1721455855789 has 2 divisors, whose sum is σ = 1721455855790. Its totient is φ = 1721455855788.

The previous prime is 1721455855741. The next prime is 1721455855813. The reversal of 1721455855789 is 9875585541271.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1288962855625 + 432493000164 = 1135325^2 + 657642^2 .

It is a cyclic number.

It is not a de Polignac number, because 1721455855789 - 2¹⁷ = 1721455724717 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1721455855289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860727927894 + 860727927895.

It is an arithmetic number, because the mean of its divisors is an integer number (860727927895).

Almost surely, 2^{1721455855789} is an apocalyptic number.

It is an amenable number.

1721455855789 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721455855789 is an equidigital number, since it uses as much as digits as its factorization.

1721455855789 is an evil number, because the sum of its binary digits is even.

The product of its digits is 141120000, while the sum is 67.

The spelling of 1721455855789 in words is "one trillion, seven hundred twenty-one billion, four hundred fifty-five million, eight hundred fifty-five thousand, seven hundred eighty-nine".