161338561 has 2 divisors, whose sum is σ = 161338562. Its totient is φ = 161338560.

The previous prime is 161338547. The next prime is 161338651. The reversal of 161338561 is 165833161.

161338561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

Together with next prime (161338651) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 160275600 + 1062961 = 12660^2 + 1031^2 .

It is a cyclic number.

It is not a de Polignac number, because 161338561 - 2¹³ = 161330369 is a prime.

It is not a weakly prime, because it can be changed into another prime (161338531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80669280 + 80669281.

It is an arithmetic number, because the mean of its divisors is an integer number (80669281).

Almost surely, 2^161338561 is an apocalyptic number.

It is an amenable number.

161338561 is a deficient number, since it is larger than the sum of its proper divisors (1).

161338561 is an equidigital number, since it uses as much as digits as its factorization.

161338561 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 34.

The square root of 161338561 is about 12701.9117065110. The cubic root of 161338561 is about 544.3932433209.

The spelling of 161338561 in words is "one hundred sixty-one million, three hundred thirty-eight thousand, five hundred sixty-one".