221161 has 4 divisors (see below), whose sum is σ = 223300. Its totient is φ = 219024.

The previous prime is 221159. The next prime is 221171. The reversal of 221161 is 161122.

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 197136 + 24025 = 444^2 + 155^2 .

It is a cyclic number.

It is not a de Polignac number, because 221161 - 2¹ = 221159 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 906 + ... + 1123.

It is an arithmetic number, because the mean of its divisors is an integer number (55825).

2²²¹¹⁶¹ is an apocalyptic number.

It is an amenable number.

221161 is a deficient number, since it is larger than the sum of its proper divisors (2139).

221161 is a wasteful number, since it uses less digits than its factorization.

221161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2138.

The product of its digits is 24, while the sum is 13.

The square root of 221161 is about 470.2775776071. The cubic root of 221161 is about 60.4741140995.

Adding to 221161 its reverse (161122), we get a palindrome (382283).

The spelling of 221161 in words is "two hundred twenty-one thousand, one hundred sixty-one".