1646632123681 has 2 divisors, whose sum is σ = 1646632123682. Its totient is φ = 1646632123680.

The previous prime is 1646632123627. The next prime is 1646632123733. The reversal of 1646632123681 is 1863212366461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1039543376400 + 607088747281 = 1019580^2 + 779159^2 .

It is a cyclic number.

It is not a de Polignac number, because 1646632123681 - 2²³ = 1646623735073 is a prime.

It is a super-3 number, since 3×1646632123681³ (a number of 38 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not a weakly prime, because it can be changed into another prime (1646632123481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 823316061840 + 823316061841.

It is an arithmetic number, because the mean of its divisors is an integer number (823316061841).

Almost surely, 2^{1646632123681} is an apocalyptic number.

It is an amenable number.

1646632123681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1646632123681 is an equidigital number, since it uses as much as digits as its factorization.

1646632123681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1492992, while the sum is 49.

The spelling of 1646632123681 in words is "one trillion, six hundred forty-six billion, six hundred thirty-two million, one hundred twenty-three thousand, six hundred eighty-one".