221745 has 8 divisors (see below), whose sum is σ = 354816. Its totient is φ = 118256.

The previous prime is 221737. The next prime is 221747. The reversal of 221745 is 547122.

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 221745 - 2³ = 221737 is a prime.

221745 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (221747) 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, 7377 + ... + 7406.

It is an arithmetic number, because the mean of its divisors is an integer number (44352).

2²²¹⁷⁴⁵ is an apocalyptic number.

It is an amenable number.

221745 is a deficient number, since it is larger than the sum of its proper divisors (133071).

221745 is a wasteful number, since it uses less digits than its factorization.

221745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14791.

The product of its digits is 560, while the sum is 21.

The square root of 221745 is about 470.8980781443. The cubic root of 221745 is about 60.5272968368.

Adding to 221745 its reverse (547122), we get a palindrome (768867).

The spelling of 221745 in words is "two hundred twenty-one thousand, seven hundred forty-five".