161091109 has 2 divisors, whose sum is σ = 161091110. Its totient is φ = 161091108.

The previous prime is 161091089. The next prime is 161091163. The reversal of 161091109 is 901190161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 153512100 + 7579009 = 12390^2 + 2753^2 .

It is a cyclic number.

It is not a de Polignac number, because 161091109 - 2¹³ = 161082917 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161091169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80545554 + 80545555.

It is an arithmetic number, because the mean of its divisors is an integer number (80545555).

Almost surely, 2^161091109 is an apocalyptic number.

It is an amenable number.

161091109 is a deficient number, since it is larger than the sum of its proper divisors (1).

161091109 is an equidigital number, since it uses as much as digits as its factorization.

161091109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 486, while the sum is 28.

The square root of 161091109 is about 12692.1672302251. The cubic root of 161091109 is about 544.1147810083.

The spelling of 161091109 in words is "one hundred sixty-one million, ninety-one thousand, one hundred nine".