2172161 has 2 divisors, whose sum is σ = 2172162. Its totient is φ = 2172160.

The previous prime is 2172151. The next prime is 2172173. The reversal of 2172161 is 1612712.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2085136 + 87025 = 1444^2 + 295^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2172161 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (2172151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1086080 + 1086081.

It is an arithmetic number, because the mean of its divisors is an integer number (1086081).

2^2172161 is an apocalyptic number.

It is an amenable number.

2172161 is a deficient number, since it is larger than the sum of its proper divisors (1).

2172161 is an equidigital number, since it uses as much as digits as its factorization.

2172161 is an evil number, because the sum of its binary digits is even.

The product of its digits is 168, while the sum is 20.

The square root of 2172161 is about 1473.8252949383. The cubic root of 2172161 is about 129.5082208821.

Adding to 2172161 its reverse (1612712), we get a palindrome (3784873).

The spelling of 2172161 in words is "two million, one hundred seventy-two thousand, one hundred sixty-one".