161606115557 has 2 divisors, whose sum is σ = 161606115558. Its totient is φ = 161606115556.

The previous prime is 161606115529. The next prime is 161606115617. The reversal of 161606115557 is 755511606161.

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., 153142299556 + 8463816001 = 391334^2 + 91999^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161606115557 is a prime.

It is a super-2 number, since 2×161606115557² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161606145557) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80803057778 + 80803057779.

It is an arithmetic number, because the mean of its divisors is an integer number (80803057779).

Almost surely, 2^161606115557 is an apocalyptic number.

It is an amenable number.

161606115557 is a deficient number, since it is larger than the sum of its proper divisors (1).

161606115557 is an equidigital number, since it uses as much as digits as its factorization.

161606115557 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 189000, while the sum is 44.

The spelling of 161606115557 in words is "one hundred sixty-one billion, six hundred six million, one hundred fifteen thousand, five hundred fifty-seven".