1812161 has 4 divisors (see below), whose sum is σ = 1951572. Its totient is φ = 1672752.

The previous prime is 1812157. The next prime is 1812199. The reversal of 1812161 is 1612181.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 323761 + 1488400 = 569^2 + 1220^2 .

It is a cyclic number.

It is not a de Polignac number, because 1812161 - 2² = 1812157 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1812121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 69686 + ... + 69711.

It is an arithmetic number, because the mean of its divisors is an integer number (487893).

2^1812161 is an apocalyptic number.

It is an amenable number.

1812161 is a deficient number, since it is larger than the sum of its proper divisors (139411).

1812161 is a wasteful number, since it uses less digits than its factorization.

1812161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 139410.

The product of its digits is 96, while the sum is 20.

The square root of 1812161 is about 1346.1652944568. The cubic root of 1812161 is about 121.9173721614.

Adding to 1812161 its sum of digits (20), we get a palindrome (1812181).

The spelling of 1812161 in words is "one million, eight hundred twelve thousand, one hundred sixty-one".