221841 has 9 divisors (see below), whose sum is σ = 322491. Its totient is φ = 146952.

The previous prime is 221831. The next prime is 221849. The reversal of 221841 is 148122.

221841 = T₄₇₀ + T₄₇₁.

The square root of 221841 is 471.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 65025 + 156816 = 255^2 + 396^2 .

It is a tau number, because it is divible by the number of its divisors (9).

It is not a de Polignac number, because 221841 - 2⁷ = 221713 is a prime.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (221849) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1335 + ... + 1491.

221841 is a Friedman number, since it can be written as (482-11)^2, using all its digits and the basic arithmetic operations.

2²²¹⁸⁴¹ is an apocalyptic number.

221841 is the 471-st square number.

221841 is the 236-th centered octagonal number.

It is an amenable number.

221841 is a deficient number, since it is larger than the sum of its proper divisors (100650).

221841 is an equidigital number, since it uses as much as digits as its factorization.

221841 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 320 (or 160 counting only the distinct ones).

The product of its digits is 128, while the sum is 18.

The cubic root of 221841 is about 60.5360302651.

Adding to 221841 its reverse (148122), we get a palindrome (369963).

The spelling of 221841 in words is "two hundred twenty-one thousand, eight hundred forty-one".