1778318661601 has 2 divisors, whose sum is σ = 1778318661602. Its totient is φ = 1778318661600.

The previous prime is 1778318661563. The next prime is 1778318661607. The reversal of 1778318661601 is 1061668138771.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1778208915025 + 109746576 = 1333495^2 + 10476^2 .

It is an emirp because it is prime and its reverse (1061668138771) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1778318661601 - 2¹³ = 1778318653409 is a prime.

It is not a weakly prime, because it can be changed into another prime (1778318661607) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 889159330800 + 889159330801.

It is an arithmetic number, because the mean of its divisors is an integer number (889159330801).

Almost surely, 2^{1778318661601} is an apocalyptic number.

It is an amenable number.

1778318661601 is a deficient number, since it is larger than the sum of its proper divisors (1).

1778318661601 is an equidigital number, since it uses as much as digits as its factorization.

1778318661601 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2032128, while the sum is 55.

The spelling of 1778318661601 in words is "one trillion, seven hundred seventy-eight billion, three hundred eighteen million, six hundred sixty-one thousand, six hundred one".