161505113909 has 2 divisors, whose sum is σ = 161505113910. Its totient is φ = 161505113908.

The previous prime is 161505113899. The next prime is 161505113993. The reversal of 161505113909 is 909311505161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 99337171684 + 62167942225 = 315178^2 + 249335^2 .

It is a cyclic number.

It is not a de Polignac number, because 161505113909 - 2²⁴ = 161488336693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161505113999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80752556954 + 80752556955.

It is an arithmetic number, because the mean of its divisors is an integer number (80752556955).

Almost surely, 2^161505113909 is an apocalyptic number.

It is an amenable number.

161505113909 is a deficient number, since it is larger than the sum of its proper divisors (1).

161505113909 is an equidigital number, since it uses as much as digits as its factorization.

161505113909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36450, while the sum is 41.

The spelling of 161505113909 in words is "one hundred sixty-one billion, five hundred five million, one hundred thirteen thousand, nine hundred nine".