221845 has 8 divisors (see below), whose sum is σ = 286776. Its totient is φ = 163776.

The previous prime is 221831. The next prime is 221849. The reversal of 221845 is 548122.

221845 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 33489 + 188356 = 183^2 + 434^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 221845 - 2⁵ = 221813 is a prime.

It is a Duffinian number.

It is a congruent number.

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 7 ways as a sum of consecutive naturals, for example, 1642 + ... + 1771.

It is an arithmetic number, because the mean of its divisors is an integer number (35847).

2²²¹⁸⁴⁵ is an apocalyptic number.

It is an amenable number.

221845 is a deficient number, since it is larger than the sum of its proper divisors (64931).

221845 is a wasteful number, since it uses less digits than its factorization.

221845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3431.

The product of its digits is 640, while the sum is 22.

The square root of 221845 is about 471.0042462654. The cubic root of 221845 is about 60.5363941033.

Adding to 221845 its reverse (548122), we get a palindrome (769967).

The spelling of 221845 in words is "two hundred twenty-one thousand, eight hundred forty-five".