161606055001681 has 2 divisors, whose sum is σ = 161606055001682. Its totient is φ = 161606055001680.

The previous prime is 161606055001663. The next prime is 161606055001739. The reversal of 161606055001681 is 186100550606161.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 103124857711681 + 58481197290000 = 10155041^2 + 7647300^2 .

It is a cyclic number.

It is not a de Polignac number, because 161606055001681 - 2¹³ = 161606054993489 is a prime.

It is a super-2 number, since 2×161606055001681² (a number of 29 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (161606056001681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80803027500840 + 80803027500841.

It is an arithmetic number, because the mean of its divisors is an integer number (80803027500841).

Almost surely, 2^{161606055001681} is an apocalyptic number.

It is an amenable number.

161606055001681 is a deficient number, since it is larger than the sum of its proper divisors (1).

161606055001681 is an equidigital number, since it uses as much as digits as its factorization.

161606055001681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 259200, while the sum is 46.

The spelling of 161606055001681 in words is "one hundred sixty-one trillion, six hundred six billion, fifty-five million, one thousand, six hundred eighty-one".