161665555559 has 2 divisors, whose sum is σ = 161665555560. Its totient is φ = 161665555558.

The previous prime is 161665555507. The next prime is 161665555619. The reversal of 161665555559 is 955555566161.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-161665555559 is a prime.

It is a super-2 number, since 2×161665555559² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 161665555498 and 161665555507.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161665558559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80832777779 + 80832777780.

It is an arithmetic number, because the mean of its divisors is an integer number (80832777780).

Almost surely, 2^161665555559 is an apocalyptic number.

161665555559 is a deficient number, since it is larger than the sum of its proper divisors (1).

161665555559 is an equidigital number, since it uses as much as digits as its factorization.

161665555559 is an evil number, because the sum of its binary digits is even.

The product of its digits is 30375000, while the sum is 59.

The spelling of 161665555559 in words is "one hundred sixty-one billion, six hundred sixty-five million, five hundred fifty-five thousand, five hundred fifty-nine".