161906389 has 2 divisors, whose sum is σ = 161906390. Its totient is φ = 161906388.

The previous prime is 161906377. The next prime is 161906411. The reversal of 161906389 is 983609161.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 122279364 + 39627025 = 11058^2 + 6295^2 .

It is a cyclic number.

It is not a de Polignac number, because 161906389 - 2²³ = 153517781 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161906369) 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, 80953194 + 80953195.

It is an arithmetic number, because the mean of its divisors is an integer number (80953195).

Almost surely, 2^161906389 is an apocalyptic number.

It is an amenable number.

161906389 is a deficient number, since it is larger than the sum of its proper divisors (1).

161906389 is an equidigital number, since it uses as much as digits as its factorization.

161906389 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 69984, while the sum is 43.

The square root of 161906389 is about 12724.2441425807. The cubic root of 161906389 is about 545.0311560900.

The spelling of 161906389 in words is "one hundred sixty-one million, nine hundred six thousand, three hundred eighty-nine".