161443561 has 4 divisors (see below), whose sum is σ = 161906500. Its totient is φ = 160980624.

The previous prime is 161443559. The next prime is 161443573. The reversal of 161443561 is 165344161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 165344161 = 71 ⋅2328791.

It can be written as a sum of positive squares in 2 ways, for example, as 131675625 + 29767936 = 11475^2 + 5456^2 .

It is a cyclic number.

It is not a de Polignac number, because 161443561 - 2¹ = 161443559 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (161443511) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 230946 + ... + 231643.

It is an arithmetic number, because the mean of its divisors is an integer number (40476625).

Almost surely, 2^161443561 is an apocalyptic number.

It is an amenable number.

161443561 is a deficient number, since it is larger than the sum of its proper divisors (462939).

161443561 is an equidigital number, since it uses as much as digits as its factorization.

161443561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 462938.

The product of its digits is 8640, while the sum is 31.

The square root of 161443561 is about 12706.0442703463. The cubic root of 161443561 is about 544.5113157238.

The spelling of 161443561 in words is "one hundred sixty-one million, four hundred forty-three thousand, five hundred sixty-one".