1680016961681 has 2 divisors, whose sum is σ = 1680016961682. Its totient is φ = 1680016961680.

The previous prime is 1680016961671. The next prime is 1680016961699. The reversal of 1680016961681 is 1861696100861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1430796353281 + 249220608400 = 1196159^2 + 499220^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1680016961681 is a prime.

It is a super-2 number, since 2×1680016961681² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1680016961671) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 840008480840 + 840008480841.

It is an arithmetic number, because the mean of its divisors is an integer number (840008480841).

Almost surely, 2^{1680016961681} is an apocalyptic number.

It is an amenable number.

1680016961681 is a deficient number, since it is larger than the sum of its proper divisors (1).

1680016961681 is an equidigital number, since it uses as much as digits as its factorization.

1680016961681 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 746496, while the sum is 53.

The spelling of 1680016961681 in words is "one trillion, six hundred eighty billion, sixteen million, nine hundred sixty-one thousand, six hundred eighty-one".