1917788045681 has 2 divisors, whose sum is σ = 1917788045682. Its totient is φ = 1917788045680.

The previous prime is 1917788045659. The next prime is 1917788045711. The reversal of 1917788045681 is 1865408877191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1914393235456 + 3394810225 = 1383616^2 + 58265^2 .

It is a cyclic number.

It is not a de Polignac number, because 1917788045681 - 2²² = 1917783851377 is a prime.

It is a super-2 number, since 2×1917788045681² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1917788045581) 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, 958894022840 + 958894022841.

It is an arithmetic number, because the mean of its divisors is an integer number (958894022841).

Almost surely, 2^{1917788045681} is an apocalyptic number.

It is an amenable number.

1917788045681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1917788045681 is an equidigital number, since it uses as much as digits as its factorization.

1917788045681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 27095040, while the sum is 65.

The spelling of 1917788045681 in words is "one trillion, nine hundred seventeen billion, seven hundred eighty-eight million, forty-five thousand, six hundred eighty-one".